I don't totally know if this site is genuine or not, but it says it donates ten grains of rice for every question you get right. I managed over 5000 grains before I got bored. And what with keeping count and all, I figure it's probably genuine.
Rice for Quizzes
It may be educational but it's still kinda fun.
So, why not make people regret their genorosity and everybody band together to gather rice?
This is one of those sites where I can be smug about my knowledge og the English Language.