Melissa Kaplan's Herps: Amphibians
Detailed information on many amphibian species by the author of Iguanas for Dummies. This site has photos and information on reptiles as well.
As it's name suggests this website is all about frogs. It includes weird frog facts, frog stories, news stories involving frogs, frog jokes, fun and games, downloadable frog pictures to print and color, an art gallery, and many photos.
Specializing in captive bred poison dart frogs, but also has care books, terrariums, and other amphibian supplies.