TheTangentBundle

It's art, Jim. But not as we know it.

Art

Society Of Figurative Arts, Forum - very talented and very knowledgeable bunch.
ConceptArt.org - resources for artists who wish to learn and share their works.
CG Society - society of digital artists.
deviantART - large community showcasing digital and traditional art of various forms.
GFXartist - large community, quality digital art, tutorials, showcases etc.
digitalart.org - a massive online gallery of digital artwork.

Historical Anatomies - anatomical atlases from yesteryear from the NIH.
Human Anatomy Pictures for Artists - anatomy references for artists. Very large collection but perhaps not as productive as a visit to the university library.
Upper and Lower Extermity Muscle Atlas - very thorough illustrations at the University of Washington.
A musculoskeletal atlas of the human body - As the name suggests.