There is an awesome site that everyone should check out. It's called FreeRice.com. Here's how it works: You get quizzed on words. Every time you get one right, you earn points towards increasing your vocabulary level. More importantly, every time you get one right, the site donates 20 grains of rice to feed starving people. Instead of simply wasting time and getting meaningless points for playing an online quiz, you FEED STARVING PEOPLE. Your knowledge is actually USEFUL.
In addition, the game is designed to actually teach you and increase your vocabulary. It's a win win. You get smarter and starving people get to eat. How often do you get a win-win in life?