I've tried a few different "shake" flashlights, and they're pretty poor performers and don't seem very practical. The light source is usually a single (sometimes a few) 5mm LED focussed through a lens, so the beam is too tight at close distances and too dim at longer distances. But, if you need light--ANY light--then at least you'll always be able to generate some light

Then there's the magnet. Apparently it's strong enough to damage magnetic stripes on credit card if you hold it close enough. Definitely don't shove it into the same pocket as your wallet! <img src="/images/graemlins/smile.gif" alt="" />

I love my crank Freeplay radio, but crank flashlights never impressed me either. It's a lot of work for not much light.

For flashlights, I'd say it's best to stick with batteries. They're cheap, and LED flashlights can make them last a long time while giving off lot's of usable light. Rotate the supply regularly or consider lithiums for longer term storage.