Literally breathing (battery life) into your mobile gadgets is quite possible.

Our pals over at The Gadgets Weblog featured a do-it-yourself breath-powered USB charger, courtesy of Instructables. All that's needed is some patience, an old CD-ROM drive, simple electronics, and some rubber bands. And a willingness to follow instructions of course.

At any rate, the contraption just needs a little engineering to keep things small and neat inside a case. Only then would moving around with it become less cumbersome, and thus more appropriate for smartphones and PDAs that draw power from a USB port.