The online racing simulator
Planet Hunters.org
(2 posts, started )
Planet Hunters.org
Help the Kepler mission find real planets.

http://www.planethunters.org/

Pretty cool you get to review actual data sets from the NASA Kepler mission. Further more if you identify a Planet you will get to share the scientific credit for doing so.
#2 - PoVo
That's quite interesting, but some of the stars thing are actually weird

Planet Hunters.org
(2 posts, started )
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