I donate to charities, and I've founded companies that have made really good products and offered great services, but I've never made the type of contribution that saves lives.
Charity doesn't work. "Human dignity is more important than wealth" (1). What we need is working economic systems, not handouts.
Have you looked at Acumen Fund? It's the organization Google.org works to spur economic development in places that need it.
http://google.org/development.html
Take a look at this presentation by Jacqueline Novogratz, the founder of Acumen:
1. http://www.ted.com/index.php/talks/view/id/157
I don't know of a place money can do more good.