Last year David Friedman from Ironic Sans conceptualised a Bulbdial clock that works like a sundial, only with LEDs. The guys at Evil Mad Scientist have gone a step further and made the clock a reality.
The only real difference between Friedman's concept and Evil's working device is that they simplified the mechanics by mounting a ring of lights at three different heights instead of a single rotating light to achieve the shadow effect. Complete instructions on how to make one yourself are available on the EMS Labs website and there is talk of producing a kit for sale. Hell, I would probably buy one. [EMS and Ironic Sans]