Christmas lights can be gaudy and distracting, or they can be a force used for good; well, as long as by "good" you mean individually-programmable and capable of showing IM status. Microsoft .NET developer Andrej Kyselica discovered that, after some tinkering, he could get a FEZ embedded controller to individually manage each LED on a string of $60 Christmas lights from Costco.
Video demo after the cut
The lights themselves are the GE Color Effects GE-35, available in 36 or 50 bulb lengths. On their own, each bulb consists of three LEDs allowing for multiple color combinations, with 14 preset patterns to choose from; however, thanks to some judicious hacking of the LED data bus, they can also be addressed by your choice of microcontroller.
Unsurprisingly, Kyselica opted for .NET, and his lights now show the various statuses of each of his IM friends (complete with Post-It notes labelling each individual). Of course, that's just one potential application.