Luminch One Offers Lumens by the Inch
I really dig Luminch One, an excellent Make: Project by Francisco Castro:
Luminch One is an interactive lamp controlled by the movements of your hand. Wave your hand over it to turn it on or off, or move your hand up or down above it to change its brightness. Inside the lamp, an Arduino hooked to an infrared distance sensor tracks your hand and sets the state and the brightness of the LED lamp.