FreeRice is a charity website with a difference.  If you go to the website, you’ll see a page containing a multiple choice question.  For every question you get right, 10 grains of rice is donated to the UN World Food Program to help end hunger.  (Banner ads at the bottom of the page pay for the rice.)

The initial game is English Vocabulary, but there are other subjects to choose from, including Famous Paintings, World Capitals and Chemical Symbols.  Each game I have tried is surprisingly addictive.  I went to the site so I could write this post and ended up donating 2000 grains of rice before I could make myself stop!