Personally, I feel that the biggest problem in developing countries is corruption. Imagine all the wealth being created to disappear into bureaucracy. I've seen police bully businesses, engineering projects finish that is woefully substandard, rigged market competition, stolen aid money, abuse of monopoly, and so on. I truly feel that this is the sauce of problems many poor people face.
I really admire Bill Gates help with poverty and education. I only wish that people start looking into anti-corruption. Maybe we should start creating anti-corruption technologies.