The Minion Rig is a free Maya rig based on the popular Minion characters from ‘Despicable Me’
Minion Rig (FREE)
Pink Panther Rig (FREE)
The Pink Panther Rig is a free character rig for Maya based on the popular character ‘Pink Panther’
Ultimate Rigs (FREE)
The Ultimate Rigs are great free Maya rigs for practicing body mechanics
Animation Buffet
Animation Buffet is a great resource for free Rigs and is constantly updated by Jean-Denis Haas (ILM)
Josh Sobel Rigs (FREE+)
Josh Sobel has some great affordable rigs (his Kayla rig is especially great). You can also get his Bonnie rig for free!
Longwinter Rigs ($10/month)
Longwinter Studios are offering access to their whole rig collection (30+) for only $10 a month. Not too shabby!
Animation Mentor Rigs (FREE)
Animation Mentor Rigs – Two free rigs from Animation Mentor when
Dota 2 Rigs (FREE)
Dota 2 Rigs – A large selection of free Dota 2 rigs on the Steam Workshop
World Zombination Rigs (FREE)
World Zombination Rigs – A free set of rigs from the game ‘World Zombination’ for use with Maya
Animator's Resource Kit 