The data that can be obtained from this is really cool. For example, "Various US Census Databases provided by The US Census Bureau" for 1980 available now and 1990 and 2000 coming soon. Definitely can be used for many useful purposes.

Open government APIs (or at least data) is here sooner than I expected.

Some great public data sets are available at Aaron Swartz's Watchdog.net in his data directory:

http://www.watchdog.net/data/

In addition check out what the Sunlight Foundation is doing making government release more data:

http://www.sunlightfoundation.com

http://faradb.sunlightfoundation.com

http://www.sunlightlabs.com

http://services.sunlightlabs.com/api/

http://www.politicalpartytime.org

GREAT idea from AWS... so many young startups are based around crunching/organizing public data. This is perfect for a site like Swivel.