Some examples include:
EcologyFund: http://www.ecologyfund.com (http://www.ecologyfund.com) (Save Habitat)
HungerSite(one of the first): http://www.thehungersite.com (http://www.thehungersite.com) (stop hunger)
Tree4life: http://www.tree4life.com (http://www.tree4life.com) (plant part of a tree)
and there are many more.
wikipedia.org dumped 2003-03-17 with terodump