Related link: http://www.lwk.dk/sketch_a_move/sketch_content.html
Louise Klinker and Anab Jain built some toy cars with touchscreens as the bodies. If you draw a squiggle or other shape on the touchscreen with an erasable pen, the car will move in a path that corresponds to the squiggle. Be sure to watch the quicktime movie.

They haven't made it yet
Really cool, but at this stage it's only a design- they don't even seem to have a prototype yet.