GravityLight has built an LED lamp that just might lift the burden. As the name implies, a weight (usually the very bag that the lamp ships in) generates electricity through natural force: the few seconds it takes to lift the weight can generate 30 minutes of light without ever replacing a battery or fuel supply.
The simple construction also has helpful side benefits, such as powering up other devices and a clip that can replace the bag with most anything that weighs around 20 pounds. The crowdfunded project's donation tiers ask $25 to donate a light to the developing world or $50 to also get one for yourself, but it's a small price to pay in the long run -- and when mass production should see prices fall below $5, the GravityLight might just change the lighting landscape for those who need it most.
What a great idea. I would encourage you to check out the crowdfunding site and consider helping out if you can.
Hat tip: BadBlue.com/Tech.