Remember the old-school "Word of the Day" idea? Well, how about you try a new word and for every new word you get right, you get to feed a child? That's the concept behind FreeRice.
The site donates rice to needy people for every word you get correct! They get paid for advertising and buy the rice with the ad money, at least that's how it sounds from when I read the site and saw the site on the news.
I have already donated about 6220 grains of rice, and I didn't even leave my chair. I suggest you try it too!