It's called Free Rice. What is it is a vocabulary site that through advertising gives away rice to developing countries. The fact page is here.
So it's a site where you can improve your vocabulary and help folks out at the same time.
If FreeRice has the rice to give, why not give it all away right now?
FreeRice is not sitting on a pile of rice―you are earning it 20 grains at a time. Here is how it works. When you play the game, advertisements appear on the bottom of your screen. The money generated by these advertisements is then used to buy the rice. So by playing, you generate the money that pays for the rice donated to hungry people.
So far my highest score is 43, with 2580 grains of rice donated. And I must say, I really don't even notice the advertising.
Rather cool eh?