Some forum threads on joint-based face rigging:
thread on Brad Noble's rig (CG Talk)
Kevin Hoffman's Tweak Rig
When building a rig like the above Tweak Rig, do you want your face-posing joints to be on a separate mesh from the jaw & eye mesh, or the same mesh?
Character Dev. & Facial Rigging Pt.1 - Jonas Avrin
automated weighting system?
Paxton Gerrish reel with joint and blendshape face rigs
Andy Van Straten reel - joint-based rig
Joint-Based Face Rig - Suchan Bajracharya
Delgo Face Curve tutorial