The last color-changing, heat-detecting showerhead was some kind of nebulous OEM product from China, but this LED Shower Light is actually purchasable from Thinkgeek. Unlike that one, this only has blue and red, but it works exactly the same: red == hot, blue == cold. Unfortunately, the red in this activates at 89 degrees, which is actually still colder than your body, so unless you like lukewarm showers, this maybe ain't so great after all. [Think Geek]