[youtube=http://www.youtube.com/watch?v=-hxZRCponks&hl=en&fs=1&rel=0][Mark Roy] designed this fine RGB LED desktop clock. It uses a PIC16F877A microcontroller and a DS1307N Real Time Clock. There is a ring of 12 RGB LEDs around the perimeter. Hours are indicated in red, minutes green, and seconds blue. If the hands overlap, the colors are mixed. Three buttons are used to set the time and it can run on as little as 0.7volts. You can find out more about the project on Stellar Core. He has plans to kit it in the future.