Craft is a site that gathers high-quality material from films, graphic novels and other visual media and lets you explore how other professionals crafted it. Giving you access to source files from animators and artists. Free Trial is available.
Splatfrog is a website with hours of lecture/demo videos by veteran animator, Ken Fountain. It has both free and paid videos.
Thinking Animation has a great section on the pros and cons of different rigs. As well as a bunch of other resources and tips across the site.
Kenny Roy is a 16 year veteran of the animation industry, and 7 year Mentor from Animation Mentor. Sign up to his members section for Monthly Videos, In-Depth Articles and more!
Animator Island is a treasure trove of animation secrets, techniques, tips, and information on your quest to become a Master Animator
Line of Action is a really useful site for learning about the human form, anatomy, speed drawing and more. Useful for both 3D and traditional animators!
Animation Mentor is an online animation school. The original online animation school taught by professional animators to grow you in the art of character animation.
iAnimate is an online animation school. They offer a complete set of workshops designed to target all animation needs, and put you in direct contact with veteran animators from the biggest & best studios in our industry.
Animschool is an online animation school. Animators from the best studios in the world work with students one-on-one, giving the students the best opportunity for growth.
Animator's Resource Kit 