via http://www.aep-emu.de/
Marat Fayzullin has ported his (commercial) NES emulator iNES to the Android platform: iNES for Android

Quote:
* Added new semi-transparent virtual joystick. Use Settings to configure, or go back to the old joystick.
* Made tactile feedback strength configurable.
* Added assignment options for diagonal buttons.
* Added persistent fast-forwarding option.
* Added low disk space warning.
* Made user-assigned key mappings override default key mappings.
* Xperia Play [X] button now acts as FIRE-A (was START before).