Found this on the net today and thought it was pretty cool. You will get a score that shows your level of vocabulary. Highest attainable score is 50 and according to the site, it will be very very difficult to get higher than 48. (That is, if you don't cheat) The more you play, the more rice gets donated, so you can feel satisfied knowing that while you increase your vocabulary, you are also sending rice to starving people via the U.N. (Don't want this turning political, just thought it was a novel website.)
Free Rice
Have fun and report your highest score if you want. Mine was 41.