This is an XSI rig I am working on in my spare time. This is the same model as my Maya rig, but it's my first foray into XSI for rigging. It's quite a powerful way to rig. There are still many things I'm working on (weighitng, facial controls, cloth dynamics, etc.) but it has stretchy spine, arms, and legs, FK/IK blending, soft eyes, etc. and uses some expressions and linking.