You may or may not be aware of this. A clockwork device dating from the ancient greeks.
Article in Scientific American
Article in Nature The Nature article also has a video.
PS: Wasn't there a sticky for cool creatures and historical discoveries around here?An ancient Greek astronomical calculator that showed the positions of the sun, Earth and the moon, and outshined any known device for 1,000 years after it, also kept track of something more mundane: when the next Olympics would take place.