From Think Geek, the Blue LED Faucet Light.

"Tired of that same old monotonous water?" "You can turn any faucet in your home into a streaming blue lagoon of techie-bliss in just minutes." "Just attach to the end of your faucet (universal adapters included), and when the water flows through the magic chamber, it simply turns on the blue LED array and illuminates the stream with a soothingly powerful crystal blue hue."

It's going on my next Think Geek order. I mean, it just has to.