Play Classic Atari games online
 

This place is pretty good:

http://www.2600online.com/

It has loads of the old Atari games that you used to get with the games-console version.
The one which came with Centipede and stuff. That was a well fun console :D

It's a Java platform, so you could even put this on your mobile phone and take an Atari 2600 where you go! :rocks: