Atari posts their classics
Some of them anyway. Go here for Adventure, Asteroids, Battlezone, Crystal Castles, Lunar Lander, and Yars’ Revenge. They look to have been recreated quite faithfully, in Flex maybe?
The mouse works in Crystal Castles. Don’t forget the level skip you can do by going to the back of the first level and jumping. 🙂

These are the actual original ROM code running on emulators which are written in flash.
–Jeff
+5 to retro cool points. -10 to American workforce productivity.
Pure Cool Ness