Evil Mad Scientist Laboratories made a cute bristlebot! They write -
The BristleBot is a simple and tiny robot with an agenda. The ingredients? One toothbrush, a battery, and a pager motor. The result? Serious fun. The BristleBot is our take on the popular vibrobot, a simple category of robot that is controlled by a single vibrating (eccentric) motor. Some neat varieties include the mint-tin version as seen in Make Magazine (check the video), and the kid’s art bot: a vibrobot with pens for feet.
HOW TO – Make a Bristlebot a tiny directional vibrobot – Link.