The website FreeRice (http://www.freerice.com) has two purposes. First, they want to help people improve their English vocabulary. The site gives you a word and four possible synonyms. Get it right, and you advance to a higher level with tougher words.
At the same time, advertisers who appear at the bottom of the screen donate 10 grains of rice per correct word to the World Food Programme, which in turn sends it to countries in need around the world.
As of now, FreeRice has paid for just under 4 billion grains of rice, hovering at around 200 million grains per day. Not bad considering it launched on October 7 with 830 grains!