Methods and systems for data interchange

1. A method, comprising:

a computing system reading a bar code in a first document, wherein the bar code encodes data and a tag that specifies a data type of the data, wherein the tag is an extensible markup language (XML) tag;

the computing system decoding the bar code to determine the data and the data type; and

the computing system using the data type to select a data field in a second document and populate the data field with the data.

2. The method of claim 1 , wherein the first document is an electronic document, and wherein the reading includes the computing system reading the bar code from a device displaying the electronic document.

3. The method of claim 1 , wherein the first document is a tangible document.

4. The method of claim 1 , further comprising:

storing the second document on a tangible medium, wherein the tangible medium includes a radio frequency identification (RFID) tag, a Smart Card, or a card having a magnetic stripe.

5. The method of claim 1 wherein the computing system is a cell phone that includes a camera configured to read the bar code.

6. The method of claim 1 , wherein the tag is a sequence of characters appended to the data.

7. A computing system, comprising:

a processor;

memory having program instructions stored therein, wherein the program instructions are executable by the processor to cause the computing system to perform:

receiving data from a data source;

generating a bar code that encodes the data and a data tag, wherein the data tag identifies a property of the data; and

transferring the bar code to a target;

wherein the receiving includes:

receiving a document having another bar code that encodes data; and

decoding the other bar code to obtain at least a portion of the data encoded in the generated bar code.

8. The computing system of claim 7 , wherein the target is a paper medium; and

wherein the computing system further comprises a printer configured to print the bar code on the paper medium.

9. The computing system of claim 7 , wherein the target is an electronic document; and

wherein the computing system further comprises a display configured to display the electronic document.

10. The computing system of claim 7 , wherein the receiving includes capturing data using optical character recognition (OCR).

11. The computing system of claim 7 , wherein the generating includes:

generating a first bar code that encodes a first set of data and a first data tag, wherein the first data tag identifies the first set of data as a person's name; and

generating a second bar code that encodes a second set of data and a data tag, wherein the second data tag identifies the second set of data as a location.

12. The computing system of claim 7 , wherein the bar code encodes encrypted data.

13. A non-transitory computer readable medium having program instructions stored thereon, wherein the program instructions are executable by a computing system to cause the computing system to perform operations comprising:

decoding a first bar code in a first document, wherein the first bar code includes data and a tag indicative of a data type of the data;

modifying the decoded data to produce updated data;

encoding a second bar code in a second document, wherein the second bar code includes the updated data and the tag; and

displaying, at a display of the computing system and via a web browser interface, a bar code that encodes data and a tag.

14. The computer readable medium of claim 13 , wherein the decoded data includes financial information about a person.

15. The computer readable medium of claim 13 , wherein the operations further comprise:

transferring the second document to another computing system.

16. The computer readable medium of claim 13 , wherein the displayed bar code is a two-dimensional bar code or a three-dimensional bar code.