http://www.freerice.com
You try to choose the right definition for the words. For each one you get correct, 10 grains of rice are donated via the UN in an effort to help end world hunger. And you can also improve your vocabulaay while doing so. So this is good, promoting education and feeding the hungry. They're able to do this because of their sponsors on the bottom of the page each time you're doing it. So far I've done 400 grains, but that's not enough for me to be satisfied with yet.