Built using a PIC16F84, about 4 hours worth of code and a few bits on a breadboard. This was the first time I've worked with PIC's so it was a learning exercise. I started with the 'Hello World' microcontroller equivalent i.e. Blinking LED, then tried the 'Knight Rider' sequencing LEDs, and then hacked this together. The code is written and assembled using the Microchip MPLAP IDE V5.70. I only did this as an exercise to familiarise myself with PIC assembler, but having got it working I decided I wanted it smaller and as I had just acquired some 12F675s I took the original 16F84 code and developed it further to work with the 12F675.
Source code (the 12F675 die source below is better documented and developed)
Hex file ready to program (right-click Save As)
Circuit schematic