This is such a cool idea I’m actually amazed that no one did it sooner. This totally beats the Maquarium.
Mouse-controlled Etch-a-Sketch, from BoingBoing
And here’s the original site: Electr-O-Sketch, which was a class project for an Electrical and Computer Engineering course at Cornell.
BTW, I’m not kidding about the Etch A Sketch Club.