Amphibian Embryology Tutorial
This site covers amphibian development from fertilization to embryo formation and includes photographs

BioInteractive
A fully interactive site about biology that includes several learning modules from the Howard Hughes Medical Institute

The Biology Project
This site is an interactive online resource for learning biology, including activities for school children, quizzes, and

Comparative Mammalian Brain Collections
This web site provides browsers with images and information from one of the world's largest collection of well-preserved, sectioned and stained brains of mammals. Viewers can see and download photographs of brains of over 100 different species of mammals (including humans) representing 17 mammalian orders