Vectorify is a powerful and free Maya tool for animators that makes it easy to repath animations
Vectorify
Pickify
Pickify is a powerful selection set tool for Maya that lets you assign a hotkey to selection sets instantly and easily hide or show parts of a geometry
Twosify
Twosify is a free tool by Ehsan Bayat for Maya that allows you to convert your animation to stepped in a non-destructive way
M-Rigs
M-Rigs are a set of stylized character rigs for Maya by Ramon Arango that can be purchased individually or as a bundle. Check them out on his Gumroad page.
Guardian Rig
Guardian Rig is a free Maya rig created by Robbie Reid, perfect for testing body mechanics and attack combos
Sticky Mod
Sticky Mod is a free deformation tool made by fRigging Awesome studio that allows you to easily move the geometry of a model. Very useful for polishing animations.
Smart Layer
Smart Layer is a script for Autodesk Maya that allows you to adjust animation using layers in a much easier and more powerful way.
IK/FK Switcher
IK/FK Switcher is a free Maya tool that allows you to build a temporary IK/FK setup on top of your original controls, while preserving animation.
She-Hulk Rig
She-Hulk Rig is a free Maya rig made by @CromaCore_. Download it from his Gumroad page!
Animator's Resource Kit 