Adults inhale and exhale on average 20 times per minute. Since you are already breathing, why not put those muscles to extra use by having them charge a USB device? Instructables has cobbled together plans to build your own USB charger from spare parts in your house; which is kind of relative as you may not have the innards of a CD-ROM drive, a non-stretching belt or band, and a simple broccoli binder in your junk drawer.

The idea is with every breath you take the band causes the gears of the CD-ROM drive to move, and with a few extra parts from the local electronics store, the movement builds up voltage that then charges your USB gadget. Unfortunately the USB Breath Charger only produces around 5 volts of power, so if you need to power your USB shaver you might want to hop on your bike and pedal up a couple really steep hills. — Stephen Schleicher

Instructables via Treehugger