Scientific Illustration Resources
Anatomy
The Human Figure in Motion
by Eadweard Muybridge, R. Taft
Eadweard Muybridge (1830 - 1904) was a photographer who studied animals and people in motion. His work is helpful to artists because it shows how to accurately portray action.
Cyclopedia Anatomicae : More Than 1,500 Illustrations of the Human and Animal Figure for the Artist
by Gyorgy Feher, Andras Szunyoghy (Illustrator)
Web Sites:
Online Image Databases 
Anatomy
Google Image Search, searchable database of images