I spent a lot of this morning beefing up on my vocab playing FreeRice. A sister site of Poverty.com, FreeRice aims to provide free access to English vocabulary, and to provide free rice to hungry people world wide by donating 20 grains of rice for each correct word you chose on their quiz. I like vocab and I like causes to end world hunger, so this site is the good way for me to wait on hold and as writer in real life, this can be a VERY helpful way to stir up the word juices in my word maker, when that, uh, stops working.
But to be honest, I don't know how much good it could be doing. Neither FreeRice or Poverty.com are listed on CharityNavigator.org or CharityWatch.org (disclosure: neither are the Wild Animal Park or CREF, which I vouch for). Some of the words seem awfully tough for a site that donates 20 grains of rice for each correct word in the quiz, however much that is, and I am not sure that lording your high scores over your friends is in keeping with the charitable spirit.
But that's really for you to decide. I don't think FreeRice is any where near being a solution, but it doesn't bill itself a one. If I have filled you with suspicion about the site, think of all the warm fuzzies you'll get from feeling smart, charitable and more verbose than your friends and check it out for yourself.