Showing the iCade 8-bitty blue-tooth game pad controller that works with the Nexus 7 - straight out of the box without having to root it or anything. It is primarily designed for use with iOS but works great with Android as well as you can see. Read more below.
The Emulators shown here made by mr Broglia all offer native iCade / iPad controller support which makes response times very fast. Remapping the buttons doesn't seem possible yet and you have to make due with the layout mr Broglia has decided upon. Most work great and some are a bit off. But that is all down to personal taste. Mr Broglia has done an excellent job on those emulators and they are definitely money well spend.
Sadly the Playstation emulators I tried are not supported by the 8-bitty or vice versa. Still you'd probably would want to use a proper dual analog controller for that I reckon. Playstation emulation is full speed and it is possible to hook up controllers over USB (Playstation3, Xbox 360 but I have had very little luck in getting those to work after the Nexus updated to the Android 4.2.1 OS. Rooting (again) should fix that.)
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