AnimProps is a website where 2D and 3D artists can create an account for free to share, sell or purchase artwork. A big resource for animation rigs.
The Animation Paper – Pre Release is now available. Currently in Alpha but check it out, download it and give feedback
Grease Pencil Rigs are a free set of basic rigs for Blender 2.8 that are for use with Grease Pencil. They are aimed to ease the drawing of characters by showing construction lines which you can use for reference while drawing.
AnimChallenge is a Facebook group that features a monthly animation challenge as well as a dedication to learning within the animation community.
Game Anim is a book by Jonathan Cooper (Naughty Dog) that de-mystifies the animation side of game development, explaining every step of the process while providing valuable insights and work philosophies
Rough Animator is a fully featured hand drawn animation application that runs on Android, iOS, Mac OS, and Windows. Currently available for $4.99