A "practice" rig for students and a display of some advanced Ae character rigging techniques.
 
Download free rig to try yourself here (CC12 & CC14 versions available):
 
 

This rig was created with help and inspiration from

Daniel Gies’ amazing work and tutorials
everyonediesfilms.com

Duik tools v14

Thanks for additional coding help from

Joe Russ at Mografi
mografi.com

Dan Ebberts at the Creative Cow Forums
forums.creativecow.net/adobe_after_effects_expressions