SCIENCE!
Encyclopedia of Life       
 This site is the Encyclopedia of Life.  It is exactly that.


The IUCN Red List of Threatened Species        
This site is the world's most comprehensive inventory of the global conservation status of plant and animal species.


World Wildlife Fund - Wildlife Conservation, Endangered Species Conservation      
 This is the home of the World Wildlife Fund.

http://www.birds.cornell.edu/netcommunity/Page.aspx?pid=1478

Cornell University Ornithology Lab:  Excellent resource for the bird project.  However, their database only covers birds confirmed in North America.  There is some overlap with species in the Caribbean.  Click on the ALL ABOUT BIRDS tab to get started.