Watsi is doing great stuff.

One related thing I would recommend, if you're interested in charity & philanthropy, is to check out GiveWell (http://givewell.org). They have very well-studied recommendations of charities, and they recommend them on the basis of "most good for your dollar". Some of the most efficient treatments on Watsi are on the order of thousands of dollars per child's life saved. That's pretty damn good as "good for your dollar" goes, but GiveWell's recommendations are often a factor of 2-10 better, and the evidence base to support their recommendations is quite strong.