Small World Experiment (6 Degrees of Separation)

 Yahoo  and Facebook are joining forces to test a social experiment that showed there are just six degrees of separation between most people on the planet.

The current Small World experiment -- anyone with a Facebook account can participate by going to http://smallworld.sandbox.yahoo.com -- could help determine that. The study is intended as academic social research and will be published in a peer-reviewed scientific journal, said Watts, a widely recognized authority on social networks.

From the Small World Experiment website:

The Small World Experiment is designed to test the hypothesis that anyone in the world can get a message to anyone else in just "six degrees of separation" by passing it from friend to friend. Sociologists have tried to prove (or disprove) this claim for decades, but it is still unresolved.

Basically you sign up as a sender. You are given a target somewhere in the world, and a message to send. Using your Facebook account you send the message to one person. That person sends it on and so it goes until it reaches the intended target. Sounds like a bit of fun and you'll be helping social research.