Grey Matter Gary is a free Maya rig from Squiggly Rigs
The Setup Machine enables Maya users to easily and quickly rig a wide variety of CG characters with just a few clicks. Generate a flexible, modern character rig in minutes saving you days or weeks of work
Animbot is an essential free Maya toolset for animators made by Alan Camilo. Highly recommended!
I Want to be an Animator is a Youtube collection of free Lessons, Tutorials and Tips about 3D Animation, mostly focusing on the basics and principles.
Fantasy Crocodile Rig is a free Maya rig that has a super appealing design.
Rocket Girl Rig is a free Maya rig from the VMComix animation blog.
Jasmine Rig is a free rig for Maya that has a load of great features!
Tri Vital has created a collection of awesome Maya rigs and put them on gumroad for free!
Keyframe MP is is a compact, yet powerful, media player designed to meet the needs of animators. Features include scrubbing (with audio), single frame stepping, an adjustable playback range and bookmarks. Free Trial available.