Besides paying for school and books and DVDs and all that ordinary stuff:
1. Money into (genetic) development of super crops (don't exhaust the soil, easy to grow in less optimal climates, etc.) I saw a Nobel Peace Prized guy on PBS who talked about this avenue of solving the world hunger crisis and I was very impressed.
2. Pool membership. (Always wanted to swim lots, never had the resources.) Maybe take that final lifeguard training class?
I don't know. Never been rich. Never had to wonder how I'd spend money.
ETA (after reading some response):
3. Invest money in microfinance (where you loan money to small businesses)- providing motivated, well-planning people with just the little necessary capital to succeed.
4. Winter trip to Yosemite.

I love Yosemite in the winter.
5. Enable more efficient giving structures. Lots of extra waste in this world that we can use I think if there is more clear, advertised ways that stuff group A doesn't need can go to group B, etc. And services lots of people can give but they don't know there's a need, or where there's a need.