GameAnim.com is a website created and run by Jonathon Cooper (Naughty Dog). It has a massive selection of animation resources from interviews, tips & tricks, showreels and much much more!
GameAnim
Tiger Rig (FREE)
The Tiger Rig is a free rig compatible with Maya 2015+
Action VFX (FREE+)
Action VFX has a collection of free VFX that are useful for adding post effects to your animations. There is also a much larger collection available for purchase.
12 Principles of Animation
12 Principles of Animation – Alan Becker has made a video series highlighting each of the 12 Principles of Animation as described by Frank Thomas and Ollie Johnston in their book “The Illusion of Life”
Josh Sobel Rigs (FREE+)
Josh Sobel has some great affordable rigs (his Kayla rig is especially great). You can also get his Bonnie rig for free!
The Animation Podcast
The Animation Podcast was a podcast by Clay Kaytis that focused on interviews from animation veterans (mainly Disney). It is no longer being updated but still has a bunch of podcasts to listen to.
Bancroft Brothers
The Bancroft Brothers is an animation podcast that provides an entertaining and educational look at animation. Tom Bancroft and Tony Bancroft discuss the art and business of animation with some of the industries biggest talents from Glenn Keane to Brad Bird to Don Hahn.
A Keyframe of Mind
A Keyframe of Mind is an animation podcast hosted by Jenny, Ju Li, Katie and Esther and discuss topics ranging from best practices, navigating the industry and the never-ending journey to improve and grow personal creativity
Syncsketch
Syncsketch is a really useful free website for posting work and receiving feedback. Just upload a video and allow others to review, draw and make notes.
Animator's Resource Kit 