The Bartleby.com online edition of Gray’s Anatomy of the Human Body features many vibrant engravings (many in color) from the classic 1918 edition.  Offers an extensive subject index and search options.

Images of mammal, bird, amphibian, reptile, fish, and crustacean skulls.

Designed for students, this site give specific instructions on the frog dissection process.  Each step is illustrated with images and has links to additional facts, movies and activities.