Radio has long been the most powerful medium in Africa. Newspapers are available only in cities or big towns. Televisions are too expensive and need power to run. A radio works on batteries or, if you're lucky enough to have a wind-up model, can be powered with a hand crank.

Which is why this project from California-based Hesperian Foundation is such a great idea. The foundation has begun broadcasting a recording of its book "HIV, Health and Your Community" across the radio airwaves in the Democratic Republic of Congo. The recordings are in English, French, Swahili and Lingala.

Hesperian is a non-profit publisher of books and educational materials "that help people take the lead in their own health care and organize to improve health conditions in their communities," according to its website.

The UN and other NGOs have used radio as a means of dissemenating messages for years. The simplest ideas are often the best.

—Simon Robinson/Johannesburg