FreeRice

REAL RICE
If you must virtual farm why not go to FreeRice, a non-profit website that is fun, has a little something in it for you, and just might do something for those really in need? The gist of the site is that it asks you vocabulary questions. The ones you miss keep sneaking back into the list so that eventually you learn it. For every correct answer the site's advertisers donate a grain of rice to the hungry. Admittedly, a grain of rice isn't much but every journey starts with the first step.
(Suggested by TOMMY BEALLE)