"When you play a game at Gwap, you aren't just having fun ... By playing our games, you're training computers to solve problems for humans all over the world."
There are a few fun, unique games on that site. My favorite is Squigl, where you and a mystery partner each trace the outline of a portion of a picture (as indicated by a clue such as "sky", "man", "clover" etc), and then you get points based on how similar your outlines are. Another of my faves is Tag a Tune, where you and a mystery partner each listen to a portion of a song, and describe it in a few keywords. Then you guess, based on they keywords, whether you are listening to the same tune. Nifty!
Best part of this site is that each week, they give away a $50 and a $20 gift certificate to amazon.com... to be entered in the draw you need to make only so many points. Come play wif meh! I am Binkatron5000, HEAR ME ROAR! EARARARAAIIPOOIUUUGH!!!... looks like I need to work on my roar.