Wind-up LED flashlight needs no batteries...so is perfect for kids
Kirsten's flashlight recommendation is perfect for summer campouts, fort play, and persistent bogeymen:
My kids love flashlights, and tend to forget to turn them off, thus using up lots of batteries. I received a pocket-sized LED wind-up flashlight as a gift. My 4 y/o son promptly took it over, and I realized that this is the flashlight for him! No batteries needed! He just winds it up himself, and if he leaves it on all night, then that's OK--just wind it up again next time you need it. It is also just the right size for the kids (ours are from L.L. Bean, but I'm sure you can find them in many places) We liked it so much, that we bought another one for our daughter to use. Besides being kid friendly, it should come in handy in an emergency.
We have two of these (one for each kid) -- we love them. Good to keep in the car, too.