Kiva(Potentially relevant link)
The Peace Corps is considered good diplomacy. Send Americans over to help community development and other countries start to like us.
Tommy Thompson wanted to send medical ships around the world to serve as roving hospitals for poor nations. Medical diplomacy.
Kiva, similarly, is about diplomacy. I don't know if donating money that way is as beneficial as donating to PATH (though you have a good chance of getting your Kiva money back to re-donate, which is pretty cool), but if pro-American diplomacy is something you support, that should be another major benefit of Kiva.
How important is it that other countries like us? Seems like if we're decent at doing good things with our foreign policy then our being popular and respected benefits everyone. If we're trying to invade non-aggressive nations based on known-to-be-false evidence, having other nations say 'Get lost'--as France did with Iraq--is a good thing. (Had Britain [and don't forget Poland!] done the same, maybe we wouldn't have gone into Iraq at all.)
For the next four years, at least, I'm guessing we'll be in the former category.