Touch Arcade has a list of the games on the App Store currently compatible with ThinkGeek's iCade arcade stand for the iPad. It's certainly more than just the one official Atari app that it was compatible with at release, but the list is still pretty short, with only 16 titles included:
No Gravity
Warblade HD
Sideways Racing
Silverfish MAX
Match Panic
Mos Speedrun
Velocispider
Super Mega Worm
Super Mega Worm Vs. Santa
Compression HD
IronStar Arena
Emerald Mine
