(Video Link)
YouTube user yankeyan altered his Kinect gaming interface so that he could play Super Mario Bros. by mimicking Mario's movements:
I programmed it to recognize my motions and passed the virtual button presses to the NES emulator. I could have placed a simulated keypad right in front of me that I can press with my hands, but I thought full body gestures were more in the spirit of Kinect. Of course, Mario isn't designed to be played like this, so this is really really hard.
via Technabob
However, this is still really impressive.