The Hunger Site
Remember them? Once upon a time in 1999 I'd visit them every morning. I've slacked off in recent years and now I hear they're having trouble getting enough people to come.
If you're not familiar with the site, you click on a link and their sponsors donate to them. The ads are not obnoxious and they feature some interesting products and gifts.
Go check it out. And while you're there, visit the tabs for The Rainforest Site, Breast Cancer Site and so on. It's too easy not to.