A man reconstructed the 2000 year old Antikythera Mechanism, an ancient "computer" built by the Greeks to keep track of the moon, the planets and cycles. It's as amazing now as it was then.
The video shows off how it worked. Turning the dial shifted the moon, the sun and planets around the Earth and let users keep track of where each was supposed to be. Michael Wright and his first working model of the Antikythera Mechanism then go on to show off stuff like keeping track of the Olympics every four years and seeing when there are going to be eclipses. That's right, they could predict eclipses—which happen on an 18-year cycle—using this device! [Neatorama via Geeksaresexy]