We had a discussion in class today about energy sources, and as I was walking out, I had an inspiration-- running a wire through the center of your bike axle, and attaching magnets to the wheels. I got really excited, and practically flew home, hoping to get some wire and a voltmeter and test it out, and while my set up was lacking, it didn't discourage me! But, more soberly, I thought 'this can't possibly be the first time someone's thought of it' ...