This site is seriously awesome -- basically, it's a vocabulary game, but for every question you get right, the site donates 20 grains of rice to the UN World Food Programme. So it's a three-fer: you improve your vocabulary, you help people in the third world, and you make a conservative angry by supporting the United Nations. My top score so far is 45, and I've donated 3000 grains of rice so far; I look forward to being topped in both categories by people here.