One of the top charities in GivingWell is to help stop malaria. You should donate. Nets go a long way and they're really cheap. I bought 20 nets last year. We don't need Bill Gates for that, right?

http://www.givewell.org/charities/top-charities

By doing really difficult and expensive medical research over decades, we will discover many things that help many of the 7 billion people, increasing to 9 billion, on the planet. Knowledge isn't something that stays locked up forever, and which only rich people have access to it.

Age related research will benefit over 10 billion people in this century. Most of us will get old.