Kibera has long been known for it's "flying toilets," or, plastic bags filled with human waste thrown into street corners or wherever there is space for them.  A recent invention is an eco-friendly version of the flying toilet, which takes the standard plastic bag, adds a biodegradable, odor-suppressant coating, and ties in fertilizer creation capabilities.  This new iteration of the flying toilet can actually create wealth from waste!
Check out the BBC article here: http://news.bbc.co.uk/2/hi/africa/8594972.stm