Updated code for: http://www.instructables.com/id/USB-NES-controller-with-an-arduino/

The existing code for the instructable was just a little out of date, this version should work with Arduino 1.0.6 and Processing 2.2.1, was tested on an Arduino Uno and an unmodified controller from a PAL NES.

Prodigity (who made the instructable) has been nice enough to let me host here, what a guy!

Lets you use an NES controller to control anything that supports up to 8 unique keystrokes, input to an NES emulator for example.

Keys mapped to WSAD (movement), GH (select/start), KL (B,A)

Honestly, follow the instructables link above for better info. It's very comprehensive.

Try the writeup on my blog.