Human Powered Electricial Generation
Basically as children play on a merry-go-round, they power a pumping system that moves water into a storage tank. The kids are doing something they would do anyway, and there's a benefit to the village as a whole.
I was thinking that it might be possible to put the same idea to work with an electrical generator. The kids play on the merry go round, and the rotation turns a generator's rotor, generating electricity. The electricity is stored in batteries and used at night.
Of course there's nothing that says this idea can't work in more developed nations as well. Putting a small generator on school playgrounds that provides power to the air conditioner might be a good thing.
What makes me think that this will work for power generation? Well, the One Laptop Per Child project has a design for a cow powered electrical dynamo (thanks One Laptop Per Child News for showing this to me), and surely kids have as much energy available as cows.