An 11-part video tutorial by Blender Cookie on the creation of a human portrait.
Kent Trammell writes:
This is a in-depth tutorial series explaining the creation of a realistic human portrait with Blender. The entire process will be covered from base mesh modeling, detail sculpting, texture painting, hair growing and styling, sub-surface scatter shading, and compositing. Some of the more time-consuming tasks will be time-lapses with commentary like modeling, sculpting, and texture painting; the other parts will be mostly real-time.