Passively populating a participant list with known contacts

1. A computer-implemented method of passively populating a list of participants of an electronic communications system, the method comprising the following operations performed by at least one processor:

maintaining, on a computer memory storage system, a participant list of users of an electronic communications system to be used by a user of the electronic communications system, wherein the participant list includes at least one user of the electronic communications system who was selected for inclusion in the participant list by the user, and further wherein the user is identified by multiple identities on the electronic communications system;

determining that the user knows multiple users who are not already included in the participant list;

as a consequence of determining that the user knows multiple users who are not already included in the participant list, identifying, as candidates for addition to the participant list, multiple of the users who were determined to be known by the user but who are not already included in the participant list;

determining a communications strength between each of the multiple identities of the user on the electronic communications system and each of the identified candidates, the determining of the communications strength including determining degrees of separation between each of the multiple identities of the user and each of the identified candidates;

combining the determined communications strengths for each of the multiple identities to obtain an overall communications strength between the user and each of the identified candidates;

for each of the identified candidates, comparing the overall communications strength between the user and that candidate with the overall communications strength between the user and each of the other identified candidates; and

based on results of comparing the overall communications strengths to each other, designating, for addition to the participant list, a group of identified candidates having higher overall communications strengths than others of the identified candidates, the group of identified candidates having the smallest degrees of separation from the user, the designating including:

accessing a maximum allowable number of users that may be added to the participants list, and

selecting, for addition to the participant list, a number of users that have the highest communications strengths, the number of users selected being not greater than the maximum allowable number of users that may be added to the participant list.

2. The method of claim 1 further comprising adding the designated users to the participant list.

3. The method of claim 2 further comprising identifying a group within the participant list to which each of the designated users should be added.

4. The method of claim 3 wherein identifying the group within the participant list comprises creating the group within the participant list.

5. The method of claim 3 wherein adding the designated users to the participant list comprises adding each of the designated users to the corresponding identified group within the participant list.

6. The method of claim 3 wherein the participant list is a buddy list of an instant messaging system, and the group within the participant list is a category within the buddy list.

7. The method of claim 3 wherein the participant list is an address book of an e-mail system, and the group within the participant list is a category within the address book.

8. The method of claim 3 wherein identifying a group within the participant list to which a designated user is to be added comprises identifying a group within the participant list that includes users of the electronic communications system that share a characteristic with the designated user.

9. The method of claim 3 wherein identifying a group within the participant list to which a designated user is to be added comprises:

identifying a group within a second participant list that includes the designated user; and

identifying a group within the participant list that corresponds to the group within the second participant list as the group within the participant list to which the designated users should be added.

10. The method of claim 9 wherein:

the participant list is a buddy list of an instant messaging system;

the group within the participant list is a category within the buddy list;

the second participant list is an address book of an e-mail system; and

the group within the second participant list is a category within the address book.

11. The method of claim 9 wherein:

the participant list is an address book of an e-mail system;

the group within the participant list is a category within the address book;

the second participant list is a buddy list of an instant messaging system; and

the group within the second participant list is a category within the buddy list.

12. The method of claim 3 wherein identifying a group within the participant list to which a designated user is to be added comprises identifying a group within the participant list that includes users of the electronic communications system that are associated with the designated user.

13. The method of claim 2 further comprising determining a number of users that may be added to the participant list.

14. The method of claim 13 wherein adding the designated users to the participant list comprises adding a number of the designated users equal to the determined number of users to be added to the participant list.

15. The method of claim 1 wherein determining that the user knows multiple users who are not already included in the participant list comprises identifying existing users of the electronic communications system that are included in a contact list maintained by the user as being known by the user.

16. The method of claim 1 wherein determining that the user knows multiple users who are not already included in the participant list comprises identifying people known to the user that are associated with an identifier used in the electronic communications system as being known to the user.

17. The method of claim 1 wherein:

determining a communications strength between each of the multiple identities of the user and each of the identified candidates comprises determining whether identified candidates include each of the multiple identities of the user in contact lists that they maintain and whether identified candidates are included in a contact list maintained by the user; and

designating the group for addition to the participant list comprises designating the identified candidates that include the user in contact lists and that are included in a contact list maintained by the user before designating the identified candidates that do not include the user in contact lists or that are not included in a contact list maintained by the user.

18. The method of claim 1 wherein:

determining a communications strength between each of the multiple identities of the user and each of the identified candidates comprises determining a number of messages sent between each of the multiple identities of the user and each of the identified candidates; and

designating the group for addition to the participant list comprises designating the identified candidates with the highest numbers of messages exchanged with the user.

19. The method of claim 1 wherein:

determining a communications strength between each of the multiple identities of the user and each of the identified candidates comprises determining a frequency with which messages between each of the multiple identities of the user and each of the identified candidates are exchanged; and

designating the group for addition to the participant list comprises designating the identified candidates that exchange messages with the user with the highest frequencies.

20. The method of claim 1 wherein:

determining a communications strength between each of the multiple identities of the user and each of the identified candidates comprises determining whether each of the identified candidates is a direct or an indirect addressee of messages from each of the multiple identities of the user; and

designating the group for addition to the participant list comprises designating the identified candidates that are direct addressees before designating the identified candidates that are indirect addressees.

21. The method of claim 1 wherein:

determining a communications strength between each of the multiple identities of the user and each of the identified candidates comprises determining whether each of the multiple identities of the user subscribes to contact information for each of the identified candidates and whether each of the identified candidates subscribes to contact information of each of the multiple identities of the user; and

designating the group for addition to the participant list comprises designating the identified candidates that are both subscribers to the user's contact information and publishers of contact information that is subscribed to by the user before designating identified candidates that are not both subscribers to the user's contact information and publishers of contact information that is subscribed to by the user.

22. The method of claim 1 wherein:

determining a communications strength between each of the multiple identities of the user and each of the identified candidates comprises determining a frequency with which messages are exchanged in a chat room between each of the multiple identities of the user and each of the identified candidates; and

designating the group for addition to the participant list comprises designating the identified candidates that exchange messages in the chat room with the user with the highest frequencies.

23. The method of claim 1 wherein:

determining a communications strength between each of the multiple identities of the user and each of the identified candidates comprises determining amounts of time for which each of the multiple identities of the user and each of the identified candidates have exchanged messages; and

designating the group for addition to the participant list comprises designating the identified candidates that have exchanged messages with the user for the longest amounts of time.

24. The method of claim 1 wherein:

determining a communications strength between each of the multiple identities of the user and each of the identified candidates comprises determining amounts of contact information for each of the multiple identities of the user held by each of the identified candidates and amounts of contact information for each of the identified candidates held by each of the multiple identities of the user; and

designating the group for addition to the participant list comprises designating the identified candidates for which the user holds the largest amounts of contact information and that hold the largest amounts of contact information for the user.

25. The method of claim 1 wherein:

determining a communications strength between each of the multiple identities of the user and each of the identified candidates comprises determining whether each of the identified candidates sends messages to each of the multiple identities of the user and receives messages from each of the multiple identities of the user; and

designating the group for addition to the participant list comprises designating the identified candidates that both send messages to the user and receive messages from the user.

26. The method of claim 1 wherein:

determining a communications strength between each of the multiple identities of the user and each of the identified candidates comprises determining communications strength between each of the identified candidates and a different user; and

designating the group for addition to the participant list comprises designating the identified candidates with the highest communications strengths with the different user.

27. The method of claim 1 wherein the electronic communications system is an instant messaging system.

28. The method of claim 1 wherein the electronic communications system is a chat system.

29. The method of claim 1 wherein the electronic communications system is an e-mail system.

30. The method of claim 1 wherein the participant list is a social network of the user.

31. The method of claim 1 wherein determining that the user knows multiple users who are not already included in the participant list includes inferring that the user knows multiple users who are not already included in the participant list.

32. The method of claim 1 further comprising:

prompting the user for confirmation that individual of the group of users designated for addition to the participant list are to be added to the participant list;

receiving confirmation from the user that particular ones of the group of users designated for addition to the participant list are to be added to the participant list; and

adding only those users to the participant list that the user confirmed were to be added to the participant list.

33. The method of claim 1 wherein identifying, as candidates for addition to the participant list, multiple of the users who were determined to be known by the user but who were not included in the participant list includes determining that some of the users who were determined to be known by the user but who were not included in the participant list are existing users of the communications system.

34. A non-transitory and tangible machine-accessible storage medium comprising a set of instructions that when executed by at least one processor, results in a machine performing operations for passively populating a list of participants of an electronic communications system, comprising:

maintaining, on a computer memory storage system, a participant list of users of an electronic communications system to be used by a user of the electronic communications system, wherein the participant list includes at least one user of the electronic communications system who was selected for inclusion in the participant list by the user, and further wherein the user is identified by multiple identities on the electronic communications system;

determining that the user knows multiple users who are not already included in the participant list;

as a consequence of determining that the user knows multiple users who are not already included in the participant list, identifying, as candidates for addition to the participant list, multiple of the users who were determined to be known by the user but who are not already included in the participant list;

determining a communications strength between each of the multiple identities of the user on the electronic communications system and each of the identified candidates, the determining of the communications strengths including determining degrees of separation between each of the multiple identities of the user and each of the identified candidates;

combining the determined communications strengths for each of the multiple identities to obtain an overall communications strength between the user and each of the identified candidates;

for each of the identified candidates, comparing the overall communications strength between the user and that candidate with the overall communications strength between the user and each of the other identified candidates; and

based on results of comparing the overall communications strengths to each other, designating, for addition to the participant list, a group of identified candidates having higher overall communications strengths than others of the identified candidates, the group of identified candidates having the smallest degrees of separation from the user, the designating including:

accessing a maximum allowable number of users that may be added to the participants list, and

selecting, for addition to the participant list, a number of users that have the highest communications strengths, the numbers of the users selected being not greater than the maximum allowable number of users that may be added to the participant list.

35. A system for passively populating a list of participants of an electronic communications system, the system comprising:

at least one processor; and

a tangible computer memory storage device storing instructions that, when executed by the processor, cause the system to:

maintain, on a computer memory storage system, a participant list of users of an electronic communications system to be used by a user of the electronic communications system, wherein the participant list includes at least one user of the electronic communications system who was selected for inclusion in the participant list by the user, and further wherein the user is identified by multiple identities on the electronic communications system;

determine that the user knows multiple users who are not already included in the participant list;

as a consequence of determining that the user knows multiple users who are not already included in the participant list, identify, as candidates for addition to the participant list, multiple of the users who were determined to be known by the user but who are not already included in the participant list;

determine a communications strength between each of the multiple identities of the user on the electronic communications system and each of the identified candidates, the determining of the communications strength including determining degrees of separation between each of the multiple identities of the user and each of the identified candidates;

combine the determined communications strengths for each of the multiple identities to obtain an overall communications strength between the user and each of the identified candidates;

for each of the identified candidates, compare the overall communications strength between the user and that candidate with the overall communications strength between the user and each of the other identified candidates; and

based on results of comparing the overall communications strengths to each other, designate, for addition to the participant list, a group of identified candidates having higher overall communications strengths than others of the identified candidates, the group of identified candidates having the smallest degrees of separation from the user, the designating of the group of identified candidates including:

accessing a maximum allowable number of users that may be added to the participant list, and

selecting, for addition to the participant list, a number of users that have the highest communications strengths, the number if the users selected being not greater than the maximum allowable number of users that may be added to the participant list.