Five years ago, the Gates Foundation put $450 million in to 43 grants designed to address the world's largest public health problems. Bill Gates notes in this article, "We were naïve when we began." In 2007, instead of making more multimillion-dollar grants, he started making hundreds of $100,000 ones:
That little won’t buy a breakthrough, but it lets scientists “moonlight” by adding new goals to their existing grants, which saves the foundation a lot of winnowing. “And,” he added, “a scientist in a developing country can do a lot with $100,000.”
The article is mostly about what went "wrong" in many of the grants--including those on dried vaccines, a lab in the box, a better banana, etc--and you should read it for a fun slice of the ups and downs of science.