Nebudroid is an upcoming Android Application thta will allow you to use your Android Phone as NES controller! It works in several different ways, for example you can actually move it around and rotate/tilt your phone to control it in car/racing games or the screen can light up with buttons as if it were a regular NES remote. Check out the video to see what I mean:
Pretty neat little app assuming it works as advertised! Keep in mind that this doesn’t work with an actual Nintendo Entertainment System but only NES emulators for your Windows XP/Vista/Win7 Computer and the developer said he will TRY to release a version for Linux and Mac OS X. Unfortunately NONE of the versions are available now (unless you donate) but the actual download page says that it will be available very, very soon.
Using your Android as an NES remote to play Mario 3 on an emulator on your PC. <Guinness Commercial> Brilliant! </Guinness Commercial>