MakeHuman is a free open-source software that allows you to create and pose 3D human characters. Useful for pose reference.
MakeHuman (FREE)
Frame by Frame (Blog)
Frame by Frame is a blog that displays sequential images from various animated films for study and appreciation. It also shows the gif to supply reference for timing.
The Fighters Generation
The Fighters Generation is a world renowned character database… featuring just about every fighting game character in existence. It boasts an unparalleled collection of the best quality artwork, pictures & animations!
Cartoon Network D.O.C
Cartoon Network D.O.C is an amazing site for viewing storyboards, model sheets, backgrounds and more from cartoon network shows.
Iamag.co
Iamag.co is a huge collection of references for walk cycles. The collection contains illustrations, sketches, model sheets and tutorials…
Brendan Body (Birds)
Brendan Body has a great post on his website which displays lots of great reference and observations on birds and flight.
Quickposes
Quickposes is a tool for art students, illustrators or anyone who wants to focus on improving their drawing skills. By practicing gesture drawing you will not only get better at recognizing certain aspects of poses, but you will also build a visual library of characters and models.
Living Lines Library
Living Lines Library is an amazing resource full of pencil tests, drawings, documentaries and more from the animation legends!
Posemaniacs
Posemaniacs is good free resource for searching for specific poses at various angles. It has 1000s of poses displayed by male and female 3D models.
Animator's Resource Kit 