How about a Glowing Orb of Doom(TM). Get a bunch of red, yellow, and blue LEDs (possibly other colors if u want), orient them into a ball shape. Perhaps you could find a translucent ball, or maybe make your own with a membrane of some type. Put the LEDs and the microcontroller inside. You might need a bunch of LEDs going around inside to make the light look evenly distributed, and not have patches of dark and light. Have the micro turn on the LEDs in various patterns. Have the reds all on, do different intensities, turn on some yellow to make it look orange. Have yellow and blue on to make a green. Have it pulsate. Bonus points for putting a microphone inside and making light patterns 'dance' to music. 8) The whole thing could hang from the ceiling by a chain, and the power cord goes up it. That way it's floating in the middle of the room or something. I'm probably going to make one of these some time, I just need the motivation.
ZachTheTerrible: You need one of these for your car.