

Just found this most satisfying (and addictive) way to practice and learn English vocabulary while performing a humanitarian service: Free Rice
You choose the best definition for a word, and for each word you get right ten grains of rice are donated to the United Nations World Food Program. If you get a word right the next word is harder, and if you get it wrong the next word is from an easier level. A bowl to the right of the word to be defined shows you the amount of rice you have donated, with a running tally. Did I mention that this word game is addictive? :)
Play and feed hungry people.