A project I have been involved with to create nice light patterns for Christmas trees and general lighting in a couple of cities in Romania.
We are using Arduino Micros which output to a couple of TLC5940-s, which, in-turn are driving some serious high current TRIAC-s. These are 12-15 meter high trees with a cobweb of wires and lights drawing a combined power of 20-30 amps.
The patterns are taken from Vixen Lights 3 by exporting the channel values on a fixed resolution and replayed on the Arduinos. (Next year we will be using SD cards to store higher res values and even longer sequences)