http://www.experimentalgameplay.com/

This was started by four grad students at Carnegie Mellon.  The point of this project was to make more than 50 new game ideas in a very small space of time.  All the games would be made in less than 7 days, by only one person, and they would all have be based around a theme.

Now the site has been redone and anybody can join and post games.  It’s really cool and there are some pretty cool games on there.

You should really check out Tower of Goo.  http://www.experimentalgameplay.com/game.php?g=1