We all know that giving money to charity is good karma, especially in these credit crunch times. Here's a website where you can donate food to the world's most needy for free and have fun at the same time.
Free Rice is a site that will entertain you for hours. It has a vocabularly test that gets progressively harder. For each answer you get right, the site donate 20 grains of rice to the United Nations World Food Program. It's really addictive.