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.
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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.