FreeRice.com is a site on which you can make a small difference in helping the poor by developing your vocabulary skills. What you do is simply click on the correct meaning of a given word. As you keep doing that, three advertisements display on the bottom of the site which pay for the rice. Every correct answer means 10 grains of rice.

Here is a nice way to contribute to Free Software projects that you like and use frequently, and get a bit of promotion for your blog in return.