If you enjoy camping and have a wind up torch then you might be able to make some modifications that allow it to charge your mobile phone. The wind up torch (or flashlight) in the video after the jump can generate around 4V of power when you crank the handle. Mixing this together with a Nokia car charger can allow you to generate enough power to charge your phone, PDA and other electronic devices. Its quite a good idea for those who travel and want the mixture of a torch and charger in one. As it is a custom device there are no prices for this. If you do happen to hack away at your torch then just make sure you use the correct testing equipment so that you do not damage the torch or electronic device.
There is something like that with a neodium magnet which work by shaking. It may be a better solution.