MHW has a short review on the "Shake Light" which is a a clear weatherproof LED flashlight that doesn't use any batteries.

To use the “Shake Light” you simply shake the flashlight, horizontally for thirty seconds and then turn it on. You should avoid shaking the flashlight vertically as it may cause the charging magnet to hit the end of the flashlight, possibly damaging the unit. You should now have light. In my case the “Shake Light” worked for five minutes and seventeen seconds on a thirty second shake.



Link: MHW