A thorough tutorial with a free rigged human skeleton.

AMC pixel factory, an independent game developer and a provider of digital content solutions for video games from Romania, has a series of tutorials on different aspects of game development. All the tutorials are free with some of them featuring awesome source files. 

The first one is about creating high-quality 3D diver:

VIDEOS

Human Body Proportions Setup using Skeleton Template and ZBrush Zspheres:

Creating Folds on Neopren Fabric: