Maya Rigs - Free and Paid

Some cool free rigs:

Sony's Zombie Rig: http://splinebomb.com/hotel-transylvania-free-zombie-rig/
Hulk Rig: http://dharmindoshi.com/blog-posts/hulk-rig-free-maya-rig/
AnimSchool Rig: http://www.animschool.com/DownloadOffer.aspx
Animation Mentor Rig: http://www.animationmentor.com/free-maya-rig/
Various!: http://www.11secondclub.com/resources

Paid Rigs:
Joe's Mega Pack: http://artofjoe.blogspot.com.tr/p/blog-page.html

Other Sources:
Great Collection of Rigs: http://animationbuffet.blogspot.com.tr/
http://www.cgmeetup.net/home/ultimate-rigs-maya-rigs-maya-character-rigs-free-maya-rigs/
http://www.creativecrash.com/maya/downloads/character-rigs/c/

There are so many good free rigs out there now, have a look on animbuffet for most needs