In the video below, Heckendorn (aka Ben Heck) demonstrates his hand-crank powered charger on his HTC EVO 4G. He stripped down the crank from a rechargeable flashlight, and then retooled it to send 5 volts of power through a mini-USB cable.
While the charger was built for Heckendorn's EVO 4G, the model could be used on most any smartphone. Not only will you be making a 'green' effort, but you might get a workout in the process. Use proper caution: if you don't know what you're doing, just use your wall charger.
Heckendorn is the author of Benheck.com, and is the creator of consumer accessories like the AudioFX 5+1 Headset, and the one-handed Access Controller for the PS2, XBOX 360, and PC.
source: benheckdotcom (YouTube) via GigaOM