About Animals/Wildlife - http://animals.about.com/
Brief articles and extensive links.

BBC - Nature - http://www.bbc.co.uk/nature/
Information about animals and the natural world. Includes facts and images for hundreds of species, videos, and games.

eWildlife - http://www.ewildlife.com/
Resource that attempts to deliver community and commerce features oriented toward those interested in wildlife. Many links.

International Field Guides - http://www.library.uiuc.edu/bix/fieldguides/main.htm
Extensive listing of field guides for plants and animals from regions outside of North America.

JungleWalk - http://www.junglewalk.com/
Collection of links to thousands of animal multimedia sites, organized by common name or by taxonomic group.

Nature.Net - http://www.nature.net/
Forums on bird watching, butterflies, herps, and miscellaneous outdoor activities.

Suite101: Wildlife - http://www.suite101.com/welcome.cfm/wildlife
Articles on various topics related to wildlife conservation