Superstar
The Hydro Powered Calculator is the most creative use of water since the invention of Kool Aid. This calculator runs off of three batteries, which in turn are powered by water. Brilliant!

The batteries inside the Hydro Powered Calculator last as long as the water does, which is anywhere from two to three months. The see-through plastic means that you can watch your calculator compute if you're feeling a tad voyeuristic. This calculator runs for $10 and is available from the links to your left. Get on it!