Energy is everywhere, we just never harvest any of it. Heck, just walking around is us burning the energy we got from eating food, but we're just letting it all go to waste. For shame!
The new electricity-generating knee brace takes care of this problem by using the movement of the joint to acquire juice. As the wearer walks, it charges itself up, presumably then allowing you to charge up your cell phone or MP3 player with the power generated by your walking. Cumbersome? Yes, but if you've gotta wear a brace for some reason anyways, you might as well get some free energy out of it.