We think the iCade is quite the awesome. Atari obviously thinks so too because they're making their own version. Called the Atari Arcade Duo Powered, it gives your iPad a classic arcade joystick and buttons to play classic Atari games.
Games like Asteroids, Centipede, Missile Command, etc. are infinitely more fun and nostalgic when played with the joystick. There's no details on how it works but it's probably similar to the iCade in that it connects to the iPad through Bluetooth. Judging from the bare bone looks of the Atari iOS controller, it might even be cheaper than the $100 price of the iCade. Available soon. [Discovery Bay Games via MacRumors]