BlenRig from Juan_Pablo Bouza, the auto rigging tool for Blender 3D recently updated to version 4 adding some great deformation features, added controls, and an updated user interface to scratch the surface. Check out and download BlenRig 4 for Blender.
“BlenRig is an Auto Rigging & Skinning System for Blender 2.5+ series. It features an adjustable rig which proportions can be changed to fit existing models, or to create a new character based on a previously rigged mesh.”
“BlenRig presents a wide range of possibilities regarding rig controls. Users can choose between FK, IK, Hinge and Stretchy controls, each mode can be activated independently for the different body parts. The system consists of an Armature and a strategically modeled Mesh Deform body cage. This allows the user to be able to skin characters with very little or no weight painting at all.”