This video from Waterloo Labs shows a bunch of young, excited interns building what amounts to a computer-controlled Etch-A-Sketch. The project uses an Xbox Kinect sensor to find the nearest point in space and then transmits that motion to an Arduino board which in turn controls stepper motors to turn the Etch-A-Sketch knobs. Sure you could just turn the knobs yourself, but where would the fun be in that?
You can pick up an Arduino board and software for about $50 these days so these sorts of wacky homebrew projects are closer to everyday reality than you’d think. Considering the highest tech I ever got in school was building a balloon powered car, to have these resources at hand would be boon to science teachers everywhere.
While you won’t be drawing the Mona Lisa with this thing, it’s a fun experiment and the video – after the gratuitous nerd intro – is pretty funny.