On each of these websites, you can click a button to support the cause -- each click creates funding, and costs you nothing! Bookmark these sites, and click once a day!
Also, Check out Free Rice. For each answer you get right, freerice.org donates 20 grains of rice to the United Nations World Food Program.
Here are some more "click to donate" websites you should check out:
Free Flour (donates one spoon of flour for each answer you get right)
The Environment Site (raises money that goes to the Surrey Wildlife Trust)
Help Thirst (donates one cup of water to World Vision for every time you win)
Ecology Fund (save 87 square feet of land for free by clicking on the "save land click here" links
Care2 Click To Donate Websites (If your a member of care2.com, you can click the links, there are all sorts of causes and links on this page)