Freerice (http://freerice.com/) is a site where you can improve your vocabulary, and, in the process, provide free rice to the world’s poor.
How it works: A word appears on the screen with four possible meanings. Click on the option you think is right. If you’ve picked the correct answer, 10 grains of rice are automatically donated by the site’s advertisers to the United Nations World Food Program.
What’s not to love about the idea? Do visit this site, and donate food to developing countries even as you ameliorate your lexicons (see, it’s working already for me).