A random thought popped into my head just now. (Mods, feel free to move this if it's in the wrong section) It involves using IR (infra-red) LEDs instead of normal (visible) LEDs to make a sign or decoration. It could be words, patterns, whatever. This means it could only be viewed with a mobile phone or camcorder. It might get everyone taping your display and telling others about it! Anyway, something to think about.