The course Non Human Character Rigging now has its first lesson available for free.
Lesson 1: (FREE) The Avastar Skeleton (includes 15 min. Video).
Lesson 2: The story of Bones (includes 15 min. video).
Lesson 3: Bone Roll Introduction (text only).
Lesson 4: Modify the Rig (text only).
Lesson 5: Fixing Bone Roll (text only).
Lesson 6: Fixing IK Targets (text only).
Lesson 7: Skinning (text only).
Also check out the Course Description.