Forkers Central

http://www.wheresgeorge.com/

This site is hilarously fun. Basically you mark and track your paper currency on the site to see how it floats around the country.

The data collected was recently used to determine a mathematical model of disease mobility.
http://www.scienceblog.com/cms/web_game ... emics_9874

Oh yeah!

I used to love that site. I think I entered about $1000 back when I was a lad.

I'm dissappointed that none of the 4 bills I had on me had been entered yet.