Nyko have announced a new line of controllers for Android devices. the Playpad series was designed with input from NVIDIA and has been optimized for Tegra games which support controller input. There's the Playpad, a mini controller that has dual analog sliders, and comes with a tablet stand and case, and the full-zied Playpad Pro, which is bigger and features a traditional console layout. Unfortunately the device only works with Android 3.0 and higher. The upside is that Nyko will release a compatibility app that will allow users to map controls for legacy games which support physical input. It's due for a Fall 2012 launch.
Android Phone, Nyko launches wireless gaming controller for Android devices