Something else just up as a preview for Maker Faire 2009: the Rotation Simulator.

This is a kinetic artwork that digitally simulates rotation and inertia. Turning the knob sequentially triggers eight solenoids arranged in a circle, giving the impression of rotation. The speed and direction is proportional to the knob rotation, and exponential decay simulates rotational friction mimicking an actual rotating object. However the only thing actually rotating is the knob! The LEDs are used as flyback diodes and flash when the magnetic field in the solenoid is switched off.

Here are the guts for those interested in the geeky stuff. As usual, follow the link for an annotated descriptions.