Here is a upcoming device that has the potential to put out 20W of power by hand crank, the solar works great when the sun comes out but this gives you the same potential when there is no sun. It's the same power source for the $100 laptop (one laptop per child), so if it is what they say it will do, it should be less that $100 I'd assume or buy the laptop and take out the power supply.

One minute of Pulling on the cable gets you:
25 minutes of cell phone (talk time)
1 hour of LED lighting
Ipod Shuffle 230 minutes
Nintendo DS 45 minutes

Website:

http://potenco.com/index.html

Video Links:

http://www.olpcnews.com/hardware/power_supply/steve_cisler_potenco.html

http://www.youtube.com/watch?v=H2OWEAMLKBQ&mode=related&search=

Colin explained that they had done research on the best kind of string, using some new synthetic material, and as backup, there are two extra sets coiled inside the housing of the device. They have designed it so that it can be hacked. For instance, by removing the cover (top picture) it could be attached to a bicycle hub and generate more than 20 watts of power.