It's fun to see what other people are designing in CAD, and 3-D printing on Shapeways. Recently, I ordered this LED cap by Virtox, to see what it looked like. It's quite tiny — only the size of a small marble, and kind of resembles a giant spore.
Earlier this year, I took a beginning electronics class, where we put together a circuit that makes an LED blink continuously. Just now, I put the cap on my blinking light and it looks pretty cool. I like the way the light glows through the semi-opaque material, and really highlights which parts of the material are thick or thin.
I have an idea for a 3-D printed lamp that would involve multiple LEDs. It would be a fun project to pursue in collaboration with someone who's well versed in electronics.