ThinkGeek's adorable iCade is genius. It turns your iPad into a little arcade! Asteroids forever! If it has a drawback, it's that, well, it kind of destroys the iPad's portability. Meet the Bluetooth Duo Gamer controller, which sheds the cabinet for a dock that'll fit in your backpack.
The Duo Gamer looks familiar, like a 6-button controller you use with some consoles. What sets it apart from other mobile controllers, the iCade (Atari's joystick arcade) is its flexibility. The Duo Gamer can be used as a handheld controller, yes, but thanks to its cartoonishly large proportions you can set it down on a surface and use it arcade style. In addition to working with the iPad, it will also work with your iPhone or iPod Touch. (It plugs into the 30-pin dock, so you'll need Apple's adapter to use it with your iPhone 5.)
The Duo Gamer is available now for $80. It's immediately compatible with 10 games, including Asphalt 6: Adrenaline HD, Brothers In Arms 2: Global Front Free, Modern Combat 3: Fallen Nation, NOVA 3, and Order & Chaos. [Gameloft]