This was born out of a coding session at our local Google Technology User Group. It is an Android app that communicates with a Google ADK board using the Open Accessory platform released by Google earlier this year (see my first Instructable for more info).
The board outputs 9 channels of PWM signals to the board, which in turn runs the main driver board, capable of supplying up to 100v at around 5A per channel (with suitable heatsinks). Where I come from most Christmas lights are "safety" lights, run at between 12-30v using a small stepdown transformer. While this adds significantly to the cost of Christmas cheer, it makes a much more easily driven set of lights using the hardware I've chosen.
I'm not going to have time to add a full 'ible on this before the big day, so you'll have to settle for this for now. I'll add full instructions, code samples and schematics in the new year.
The software can record and play back a light sequence synchronized with a music track. Interface is multi-touch, so you can control multiple channels at the same, plus you can edit parts of a sequence when playing back. I hope you've enjoyed it - post a comment if you're keen for me to do a full instructable!