Free Rice is not only cool for the it's purpose - to give away rice through the United Nations World Food Program, it's also an addictive vocabulary game. Huh?
From the FAQ:
How does the FreeRice vocabulary program work?
FreeRice has a custom database containing thousands of words at varying degrees of difficulty. There are words appropriate for people just learning English and words that will challenge the most scholarly professors. In between are thousands of words for students, business people, homemakers, doctors, truck drivers, retired people… everyone!
FreeRice automatically adjusts to your level of vocabulary. It starts by giving you words at different levels of difficulty and then, based on how you do, assigns you an approximate starting level. You then determine a more exact level for yourself as you play. When you get a word wrong, you go to an easier level. When you get three words in a row right, you go to a harder level. This one-to-three ratio is best for keeping you at the “outer fringe” of your vocabulary, where learning can take place.
There are 50 levels in all, but it is rare for people to get above level 48.
If FreeRice has the rice to give, why not give it all away right now?
FreeRice is not sitting on a pile of rice―you are earning it 10 grains at a time. Here is how it works. When you play the game, advertisements appear on the bottom of your screen. The money generated by these advertisements is then used to buy the rice. So by playing, you generate the money that pays for the rice donated to hungry people.
If you are a "wordie," or simply find the free rice part to be an interesting concept, take a look. So far I have donated 600 grains of rice!