The H2Glow - Temperature Sensitive LED Faucet Light is simply beyond cool. Simply connect one to a water faucet, turn on the water and watch in amazement as it makes water glow blue if the water is cool or red if the water is hot using bright built-in LEDs. It automatically turns on and off based on water flow and since you will be playing with it constantly and showing it off to everyone, it also has a built in flow-limiter designed to save you money on your water bill (only 2gpm). Best of all, since it provides a unique visual indication of water temperature, it makes it much safer for children (and you) from getting burned by hot scalding water. It would also be really cool in nightclub restrooms.
H2Glow - Temperature Sensitive LED Faucet Light