Light up the water coming out of your faucet: http://www.sciencetoystore.com/index.html?lang=en-us&target=d26.html
REALLY cool looking. And check out the other stuff the science toy store has to offer. If anything might appeal to a gifting minded caver for a gifted individual- this is a place with some really cool shit. I especially like the moo mixer mug.... 'Love that chocolate milk. -WaV
