We made a little 'Knight Rider Light Bar' using a strip 15 red and 3 blue LED's and a cheap Atmel micro controller.
LEDs are driven by a few transistors, the blue LEDs are connected together. Every led is connected to one io-port on the Atmel µC. To save costs and IO Ports no crystal is used (who cares about timing here).
There was no reason to save space in the micro controller so we made the software as simple as possible. Everybody should be able to change the patters and understand the inner workings.Read more about this silly project