If you have a few minutes, point your browser to FreeRice.com but you'd better bring your brain! I just spent just a few minutes and helped them donate over 1000 grains -- and you can too, just give it a try.
You are given a vocabulary word, and all you need to do is, "click on the answer that best defines the word." For each word you get right, they will donate 20 grains of rice to the United Nations World Food Program.
This is really innovative and a brilliant idea: create a vocabulary game to help folks learn English vocabulary (and test their wits), and donate all the advertising proceeds to a worthy cause. Simple, huh? The site launched in October, 2007 and they have already donated more than 12,369,264,510 grains of rice. That seems like a lot of rice!
It's easy to play and it feels good to do something good for someone... Why not give it a try?