Animation

Principles of Traditional Animation applied to 3D character animation - by John Lasseter
Principles of animation: Toy Story - The animation principles as seem in Toy Story.
24 fundamental principles of animation - More on the principles of animation.
Character Animation Theories And Principles - by Mike Brown.
Animation Meat - A big collection of animation related material.
Animation Arena - A great resource for animation related material.
Big Animation - Animation articles and news.
Animation Notes - by Ollie Johnston.
Carlos Baena's animation material - A big set of animation links.
Carlos Baena's animation book recommendations - Book recommendations.
Inspiring Animation Reels - Huge collection of animators' sites.
Animation tips - A LOT of good animation notes here.

References

Body language in animations - Analyzing gestures using Wallace and Grommit as reference
Getty Images - Good quality image and video database.
Framepool - Search through a huge collection of video clips.
Fineart.sk - Human anatomy references for 3D and traditional artists
Zayats tips - A collection of advice on animation and the industry.
Basic action references - 2D and, 3D reference for basic motions.
Artnatomy - Facial expression and muscles reference
Picsearch - Search engine for pictures and animations.
Biomotion Lab - Walk cycle references
Blinks - by Shawn Kelly
The Face - By Shawn Kelly
Bodybuilder Gallery - Great photo references for muscles.
Muscle Directory - Great diagram references for muscles.
Skullduggery - References of animal skulls
Global Effects - Costume references
Silent Ladies & Gents - Tons of photos of silent movie stars

Tutorials

Keith Lango Tutorials - A very nice collection of articles by Keith Lango.
Walk cycle tutorial - by Dermot O'Connor
Walk cycle tutorial #2 - by Mike Brown
Drawing for Classical Animation -A big collection of notes on drawing for animation
Storyboarding Tutorial - by Wade Konowalchuk
Ben Mathis' Tutorials - A big collection of great tutorials.
Other Artists

Paul Neale
Robert Clark
Eddie Faria
Mathieson Facer
Jason Labbe
Stephan Perreault
Hayao Miyazaki
Feng Zhu
Conceptart.org - A collection of some great artists. A ton of nice work on the forum here.
Art History - A database of artists throughout history and their works