The rig above is currently what I'm working on now in my spare time. The Diablo rig features IK/FK switching controls using a 3-chain setup, blend shapes and several MEL expressions that drive the curvature (strength) of the tail. The mouths on the shoulders feature several specific IK controls as well that drive the movements of the shoulder mouths.

I'm currently in the process of adding several driven keys for easy hand controls. After that, I'm considering adding some dynamics to the shoulder heads so that they can actually breathe fire.