Want to plays some cool games that will keep you interested for about five minutes? Both of these sites have cool little applets (that are Java and Flashed based) that will keep you interested for a very short period of time.
You can play a 'Massively Multiplayer Pong'. You and lots of your closest friends whom you don't know try to work together over the Internet to play a game of Pong. All the moves that all the players make are averaged, then the paddle is moved accordingly.
You can also play a cool 'Magic Cube 4D Applet' game. It's a Rubik's Cube in the forth dimension.