Encyclopaedia Britannica is an online encyclopedia. Start with the elementary edition. Click on the speaker, and it will read the paragraph to you!
African Wildlife Federation Wildlife Gallery has information on many threatened animals in Africa. Make sure to click on the learn more link.
Arkive is a great place to find picture, videos, and information about animals. Use the search box to find your animal. Then click on the tabs in the description box on the right to find more information about your animal.
National Georgraphic for Kids offers information on many animals. There are facts, photos, maps, and sometimes even video clips or sound.
Smithsonian National Zoological Park offers information on many animals. Just click on the proper animal category (mammal, reptile, etc...) to get started.