I ran into this site a while back but just getting around to posting on this great reference. Scott Eaton shows off his Artistic Anatomy, Digital Sculpture and VFX. There is a category over on the side under Courses & Reference titled: Bodies in Motion Image Library. He has a ton of images of single frames of motion all put next to each other to show you the break-down of the motion.
So have a look around and check out some cool ref.