Stewart

Head over here to read up on all the goodies and especially where and how you're allowed to use the rig!

Sophia

Download the rig from Sharecg.com.

Low Poly Micro Rigs

These are not free ($10 each), but they're cute. Don't remember how I found them and there could be more out there like that but so far there's this:

Low Poly Micro Werewolf Otis




Low Poly Micro Zombie Brian

 

Low Poly Micro Skeleton Tom




Low Poly Micro Mummy Taal



Low Ply Micro Orc Gronk



Low Poly Micro Dragon Fino



Low Poly Micro Ghost Hubert



Micro Cat Cloe



Micro Cow Ulli



Micro Pig Melvin



Micro Rooster Rudy

Willy

More information about Willy the rig can found in the 11secondclub thread.

Batman Beyond

Find out more about it here.

Bill The Sailor

Find out more about it here.

Drone Ship

You can download this rig directly from here (in zip form), thanks for Dharmin Doshi.

Black Panther

Head over to Turbosquid for the download link and if you want to see all the rigs he's offering (although the rest is not free, but cheap nonetheless), head over here.

Patrick

Not free, but not expensive either, check out the Patrick rig at longwinterstudios.com and watch the clips below:

Dog

Find out more about it here.

Rexxy

This cute looking rig is by Neil Easton and the link for direct download is here. Below is a test showcasing the rig. Thanks Neil for sharing it!

Ben

Find out more about it here.

RC

Find out more about it here. (link is dead, anybody found it somewhere else?)

Kien

Head over here and grab the rig by either tweeting or posting on Facebook about it. The actual site needs registration. Looks to be all free (I haven't signed up yet).

Bonnie

Find out more about it here, including demo and sample clips.

Alex

Find out more about it here. Download it here.

Günter

This is a cool looking rig, just be advised that it's not free (only $30 though). You can get it here and check out the blog here.

Flower

 Find out more about it here.

The External World Rigs

 From David OReilly

"I’ve decided to release all 65 character rigs from my short film The External World as a free download. You can use and modify them in any way you like as long as it’s for a non-commercial purpose. Showreels, short films, indie games, all that stuff is cool - just give credit. If it’s web based - include a link to my site."

There you go, pretty cool!

Head over here for more info and the download link. 

Boolieman

Find out more about it here.
Not a free rig but I thought it was worth posting since it's an interesting rig.

The Boolieman Rig | Claymation rig for Maya from Brent Forrest on Vimeo.