Now I've found a way I can. Thanks to The Publicity Hound, Joan Stewart, I learned about Good Search. Whenever you use their search engine, GoodSearch donates money to the nonprofits and charities of your choosing. Just go to GoodSearch, choose your charity, and enter your search terms. It's based on Yahoo! Search, and you can even add a local charity or school of your choice to the list.
As an info-packrat I do a lot of searching. Now that I've added GoodSearch to my Firefox toolbar (they make it easy), each of those searches will generate a donation for my choice, Heifer International. True, it's only pennies a day, but they will add up. GoodSearch is a great idea – give it a try and know that your searching will help a cause that matters to you.