Here is a great archive, though hard to navigate (browse doesn't seem to work): http://wwwihm.nlm.nih.gov/cgi-bin/gw_44_3/chameleon?skin=nlm
These are especially good: http://www.nlm.nih.gov/exhibition/horse/gallery.html
Also: http://www.nlm.nih.gov/exhibition/dreamanatomy/da_gallery.html
Many fine images are buried here: http://profiles.nlm.nih.gov/
And also: http://www.nlm.nih.gov/exhibition/historicalanatomies/intro.html
