Charging battery-free lights typically requires either low-efficiency solar panels or endless cranking. Not with GravityLight. Instead, GravityLight is powered by – you guessed it – gravity. Just lift a weight (a bag of sand or rocks, for example) at the end of its ripcord-like strap for roughly 30 minutes of power, as it slowly descends. Light output from the three LEDs is adjustable and roughly equivalent to that of a kerosene lamp; positive/negative contacts for charging small devices are an added bonus. Perfect for developing countries, which happens to be where most of these are heading with your help.

Read more at IndieGoGo – $50