After setting up my family for life, I'd use the rest to start a micro-lending company for small businesses to get started or expand. I'd open them next to dollar stores and hire lots of bilingual people. We'd have free business plan advice, too. For fun I'd buy houses in lousy neighborhoods, fix them up and fit them out with solar and geothermal systems, then offer to trade the house with a neighbor and repeat the process. This would cost money but a billion can go a long way one house at a time and see step one.