It's the holy grail of futurists, scientists, and engineers everywhere: a perpetual motion machine. A machine that runs forever and ever, never needing batteries or power. Just think of the applications of such a device, whatever form it took. You would basically unlock the secrets to unlimited power generation. Sadly, this holy grail hasn't been found yet.
But we have found something, and like the clichés say, it was inside us all along. This fan, pictured, is powered completely though the heat energy of the human hand. Assuming its parts don't wear out, and the user keeps eating, it'll go on forever and ever, purely off body chemistry. This may look like a desk novelty, but it's actually a significant step forward in technology.