The U.S. Fish and Wildlife Service maintains a website about endangered species
There is also the Environmental Online Conservation System website
Kids' Planet explains the Endangered Species Act and has information on endangered species by continent
The IUCN keeps a list of threatened and endangered species
National Geographic has amazing photographs and information about endangered species
United for Wildlife strives to raise awareness of illegal wildlife trade
There are several charitable foundations that have information about endangered species on their websites (donations are not necessary to visit the website and obtain information):
World Wildlife Foundation (has a species directory)
Wildscreen Arkive
Endangered Species International
