I have a small shake flashlight, a bit bigger than a mini-mag. A lot of work to get the light operating, even the kids lose interest in shaking it. Once you do get a sufficient charge it seems to run OK with a few shakes occasionally. Not sure how long the charge stays while the light is off. Charge-ability of the larger form factor lights might be better (Bigger magnet). Certainly a last ditch light source.

I have a crank light also, purchased pretty cheap at the local home store. I find that it works better than the shake light, the cranking was not as much work. Has 3 LEDs and 2 options, one light on or all three on. Brightness is not bad. This light does have a chargeable battery internal that holds the charge from the cranking. I found a review at Flashlight Reviews. Not the same crank light I have, but looks very similar (mine does not have a blink mode).