Here is some info on how the shaker flashlights work. As you can see, its a really simple device.
HowStuffWorks Autopsy - Inside a Shaker Flashlight
For those who know a bit more about electronics. How could we beef up this design to crank out more wattage? Is it just more coil windings and/or a stronger magnet? Or, are we looking at multiple coils and/or magnets?