Check out this article in the New York Times about a man who brought solar powered flashlights to many villages in Africa:
The inspiration for the flashlight hit him, he said, while working for Perenco in Asmara, Eritrea. One Sunday he visited a local dump to watch scavenging by baboons and birds of prey, and came upon a group of homeless boys who had adopted the dump as their home.
They took him home to a rural village where he noticed that many people had nothing to light their homes, schools and clinics at night.
With a little research, he discovered that close to two billion people around the world go without affordable access to light.