There are dance pads in the market that sense a dancer's movements and feed that input to a computer. The computer matches these with it’s own set of movements to decide the ‘points’ a dancer/user gets.

We (I + two others) reverse engineered the dance pad to make music out of it. The prototype we made involved the use of a commercial dance pad, a Wii Remote and a Beagleboard.

We also happened to write a NIME paper on this, so check it out here (The paper is 6MB in size because of hq images. Sorry, some patience needed for slower connections).