Was in B.A.M. (Books a Million) getting something and my son picked up a small 3 LED keychain light. It was $4.99 and it was about 1 1/2 x 1 1/2 inches (square). Of course my son...ok me too....played with it. It was pretty bright with those 3 LED bulbs. What caught my attention was that one side of it was a small solar panel....
Now I don't pretent that it is of world class engineering and I don't know how well it is made or how long the 'battery' inside will last (or how many cycles)...but for $5, I think I'll be picking up 1 or 2 for the kids....at least I wouldn't have to worry about buying replacement batteries (LOL).
Just a thought.....