Customizable/Pre-made character Rigs for Blender (Use Motion Capture for even more fun!)

Premade, customizable, royalty free, open-source character rigs for Blender. These are really awesome because they have built in Inverse Kinematics and facial expression control. They can also be sculpted/skinned with your own character design.

Ludwig--a more cartoony/squash & stretch character:

http://jasonpierce.animadillo.com/resource/ludwig/ludwig.html

Mancandy--a more realistic/stiff character:

http://freefac.org/posts/mancandy-248-rc1

To use in combination with these characters, there are several free Motion Capture libraries on the web, these are just a few (Blender can import .c3d and .bvh files, which both of these sites have):

http://accad.osu.edu/research/mocap/mocap_data.htm#

http://www.mocapdata.com/index.cgi