Just a heads up: I have a very interesting and detailed project to report on very soon. It's a digital clock. But a digital clock unlike any other you've ever seen. It is Arduino-based, makes use of a 7-segment LED controller, real-time clock board, DC motor controller with closed-loop feedback (YES - A MOTOR), a sweet contour-milled, machined aluminum housing, some unique optics, and other fun stuff.
It will take awhile to fully document - expect to see it within a month or so. I may soon be posting the DC motor control code separately as this should have good general use for many people. I've yet to see a nicely packaged DC motor control system w/ closed-loop feedback (PD controller) fully documented for the Arduino.