In rural Africa, electricity is hard to come by. That's why Dr. Cedrick Ngalande has developed the Green Erg Generator—a dynamo that produces electricity from friction generated with the ground while walking.
"This is basically a dynamo which is being driven as a result of friction between the ground and the blocks. The small yellowish blocks (these are covered by rubber in the real commercial product) rotate as you pull it. They are designed to rotate even on bumpy run even roads. We have tested it on moist lawns and have worked. It is very smooth so much that you basically don't feel any disturbance as you move along.
At normal walking speeds we have gotten more than 2 watts which is more than enough for running cell phones or radios. I envision that people will attach this to themselves and walk with it - or even attach it to an ox-cart, a skating board, bike, etc."
It seems absurd (and it certainly looks absurd), but harnessing wasted movement to generate electricity is an idea that has a lot of potential.