- A new spine controller that more easily and cleanly poses the spine.  
- The head controller is no longer IK based, which was kind of annoying to work with as the IK would interfere with the spine posing a lot to keep the IK flexible. Now the neck bones are independently poseable without restriction. The head controller still has full control over the head rotation regardless of what the posing of the neck and other bones further down the hierarchy, it just no longer affects its location, as it was too much of a hassle.  
- Added more sophisticated twist bones for the entire length of the front legs, as well as a single twist bone at the top of the thigh to help prevent bad deformations around the butt when the thighs twist.  
- Configured the rig to allow for scaling of any individual bone for the legs without the scaling being inherited by the child bones along the hierarchy. This for example allows the front legs to more easily be configured to be perfectly straight during a sit pose like this one! Her front legs are 90% their normal length, which isn't too much, but at 100%, there would be a lot more leg bending that I didn't find desirable. Now that's easily able to be resolved.  
- The neck bones now allow full control of stretching regardless of the posing of the neck bone (stretching before was limited to the IK from the head if the controller was moved too far away unless the neck bones stretched).  
- Pinkie's mane specifically now has what are called "Wiggle Bones", which are basically Jiggle Physics you see used in games, especially for things like clothes and hair. This'll be far more apparent in animation. Her tail still needs to be fully manually posed if it's low enough to intersect with the ground, as the Wiggle Bones currently don't support collision to a sufficient level.