Adrienne So writes a great article about finding a better alternative to the solar powered bra (since you can't just go in your bra on the street).

She proposes using breast bounce as an energy source to power up her ipod!

It's just a matter of finding the sweet spot, between reducing motion to the point where it's comfortable but still allowing enough motion to power your iPod Let's face it—if you're a double-A marathoner, you're probably not going to get that iPod up and running,

Says LaJean Lawson, who's been studing breast motion since 1985.

There is one weird fact about the article though, she mentions that while B cups can move one inch in a high support bra, a D cup can move up to 35 inches in a low support bra!. I really think that she meant centimeters, which is still a long distance to breast to travel up and down! Ouch!

But 35 inches is roughly a yard, now... boobs don't bounce half a yard each way, at least not the D cups I know!