I just came across the Mercy Ship web site. Doctors on hospital ships tour developing nations and provide free medical care to people that badly need it. In many cases, they perform surgery to remove horribly disfiguring tumors.
This blog does a great job of providing insight into what it's like to work on a Mercy Ship, with some stunning but disturbing examples of the difference their help can make. After visiting the site, I felt compelled to make a donation; just a few dollars can make a huge difference to someone's life.