Students at the MIT Sloan School of Management have drawn up a business model for a company called Sanergy ("It begins with sanitation and ends with energy"). The idea is to build a network of "sanitation units" (read: outhouses) in Kenya, collect and process the waste, and then convert it into energy and fertilizer.
If their plan works it could generate jobs and profits along every step. They're still in the early stages though. Follow their progress at the Sanergy site.