Sintex Industries' aptly-dubbed biogas digester is most certainly not the first of its kind, but it is somewhat commendable that its maker is making no bones about this thing's purpose. Destined to "solve India's energy and sanitation problems in one stroke," this concoction can convert "human [waste], cow dung, or kitchen garbage into fuel that can be used for cooking or generating electricity." Reportedly, a one-cubic-meter digester would sell for around $425, but could pay for itself in energy savings in under 24 months. Excrement to energy -- now there's a concept.