Smithsonian National Zoological Park - More than a zoo site, this resource has information about species, webcams for real time observation of animals, teaching resources and information on preservation of species. There are printable versions of almost every page which makes this a handy resource for learning "on the go".
San Diego Zoo's Video Spotlights - Can't take a trip to the San Diego Zoo? You can still enjoy the diversity of animal life through this video library. You'll be amazed with the number of videos that are available. There are videos of animal babies and animal events. In addition, the site contains lots of information on animals available through the drop-down menu labeled "Learn".
National Wildlife Federation - Wildlife, Keeping the Wild Alive is a sub-site conveying the importance of preserving our wildlife. Facts, articles, and threats are shared on a variety of wild animal species. The Backyard Wildlife Habitat sub-site shares information on common species found near our homes.
Animal Diversity Web - From the University of Michigan Museum of Zoology, this site contains classification information, species information, images, and search capabilities. The Teacher's section has resource links and lesson plan information. My favorite part of this site are the "sound bites", which are sound files of animal calls. For each animal phylum and species, there are pictures, sounds, specimens, and classification information.
Animal Planet - Offered by the Discovery Channel, this site has solid information on many species of animals. The content is primarily text-based, easy to navigate, and is referenced by animal category and species. While the informational content is great, this site does have an occassional annoying pop-up.
New Hampshire Public Television's Nature Works - Look in the "Nature Files" to find a long list of species. Click on any species to see a photo and learn about the creature's characteristics, habitat, eating, etc.
Discovery School Animal Lesson Plans - The Discovery Channel's lesson plans are thorough, printable, and contain interactive elements. They are categorized by grade level as well as by topic. The uniformity of the plans makes them easy to use and thorough.