Alejandro Garcia has a huge Youtube video series all about physics in animation, covering topics like forces, weight shift, jumping and more!
Alejandro Garcia
Morgan Loomis Tools
Morgan Loomis has a bunch of great animation tools and scripts for Maya on his website free to download. You can download the full animation shelf or get them individually!
Animsquad
Animsquad is an online animation school that has courses of all levels that include advice from industry veterans, individual masterclasses and high quality rigs.
Gnomon Workshop
Gnomon Workshop has a wide selection of animation courses from performance and acting, creating game ready animations and more!
Animation Buffet
Animation Buffet is a great resource for free Rigs and is constantly updated by Jean-Denis Haas (ILM)
GameAnim
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!
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.
Animstate Forum
Animstate Forum is filled with some amazing industry veterans and also has a lot of other resources across the rest of the website.
Animator's Resource Kit 