As long as mentioning big projects like this, I'm a fan of givewell.org. Originally they just measured various charities effectiveness, though now they also offer to operate as a (fairly transparent) pass-through. I'm sure charity navigator is pretty good too, but I have vague memories of some issues that made me prefer GiveWell... if anyone else has anything more concrete to say for or against CharityNavigator, I'd be curious to have recollection refreshed/updated.