This is a pretty cool project. It's a site that asks you vocabulary questions and donates ten grains of rice for every question you get right to feed people in famine situations. It really is an ingenious idea. They get the revenue to pay for the rice by having sponsor's ads at the bottom of every question. The more traffic they get, the more exposure the sponsors get, the more rice the famished get, and the users get a better command of the English language. It's a win, win, win situation.
As a reference it takes 7250 grains of rice to equal a cup.
Free Rice Project