Here is the Rigify tutorial. It's a looong video but I thought it'd be nice to have everything in one session. It goes step by step through the entire process, including:
Preparing the mesh
Creating vertex groups (makes rigging easier)
Creating the meta rig
Appending eye and teeth bones (standard rig does not work with unity)
Appending bones for long hair
Attaching the rig
Weight painting
This is the early release. I will add bookmarks shortly.