This is a Do-It-Yourself project from Instructables, and it's pretty cool. rubber bands, parts from an old CD-Rom drive, and a simple circuit is the ticket to charging a device that can be charged via USB. Assembly required, of course.

A USB port only passes 5 volts, so it's not like you have to generate a lot of energy. I'm just surprised breathing is enough to generate 5 volts. If they say it works...

Via Treehugger