Check out this interesing, literally illuminating, idea: The Soccket Ball is a soccer ball that generates power the more you play with it.
Weighing just a bit more than a standard soccer ball, the Soccket Ball includes an internal power-generating pendulum that harnesses and stores the power created throught its use. Millions of people in the developing world lack access to clean and safe electricity. Potentiall, this innovative device gives them a way to produce power with every kick.
Check out this short video for more information.