A Pedal Power Generator converts human power to electricity. These compact generators can be operated by pedaling (like a bicycle) or hand cranked, and can be used to charge a dead car battery, run emergency back-up lighting, or power a television. According to Howstuffworks(1), a bicycle generator can even power a laptop computer... plus it's a great way to exercise. Also check out David Butcher's excellent Pedal Generator Tutorial(2).

1. http://computer.howstuffworks.com/question658.htm
2. http://www.los-gatos.ca.us/davidbu/pedgen.html