Hi everybody,
i made a wall clock from an instrument cluster of a Mercedes-Benz SL-class. I'm using the speedometer to display hours (e.g. 70 km/h = 7 hours) and the tachometer to display minutes (5500 rpm = 55 minutes).
The stepper motors of the instrument cluster are connected to a MotorShield which sits on top of an Arduino Diecimilia.
The Arduino also decodes the time signal which is received by an external longwave time-signal receiver.
Image: http://www.flickr.com/photos/wabba1/4857744064/
Video: http://www.flickr.com/photos/wabba1/4859009203/ (I still have a small positioning problem)