Outside of metropolitan Manila in the Philippines, there are an astonishing 3 million households living without adequate power and electric lighting. A nonprofit called the MyShelter Foundation, working in conjunction with MIT students, has an ingenious program in place to bring free light to these areas:
Isang Litrong Liwanag (A Liter of Light), is a sustainable lighting project which aims to bring the eco-friendly Solar Bottle Bulb to disprivileged communities nationwide. Designed and developed by students from the Massachusetts Institute of Technology (MIT), the Solar Bottle Bulb is based on the principles of Appropriate Technologies—a concept that provides simple and easily replicable technologies that address basic needs in developing communities.
The video says it all, and you'll be surprised at how bright the "bulb" is. (And if you're wondering what the bleach is for—I initially thought it might have phosphorescent properties—it's to prevent algae from forming and clouding the "bulb.")