I started last year with a Teensy++2.0, which was overkill for such a simple project, but it was really fast to get it up and going with the Arduino IDE and Hallowe'en was fast approaching. The one advantage of using the Teensy was that I could PWM fade from one colour on the RGB LED to another.

This year I converted it to use an MSP430. This meant that I couldn't PWM fade between colours anymore, but that's not a big loss. The launchpad comes with two MSP430 chips, the better of which was in the dev board. I plan on swapping out the better controller with the less powerful one before I'm done.

For next year, I want to fit the microcontroller and other parts into the batter case to make is self enclosed.