This is something I started a while ago, but only recently found the time to complete. I call it an action pivot. It's a unique controller which uses an enhanced form of space switching to assume a keyable authority over a rig's body controller. What makes this different than typical space switching is that it uses a python script to compensate for the "jump" which occurs in the switch; this lesser known method is called space matching.
Basically this is a second body controller you can move freely and key on and off with no jumping. The idea was that you would use this to aid in blocking acrobatic movements where you need the body to rotate on a different pivot than it currently does.
I put this animation together last night as a way of testing the controller. This test was successful, but I'm not sure how practical a controller like this will be. Its use is tricky and will require further development. After that, it will need to have its controls connected to an attribute so you don't need a python panel to key your switching. Regardless of where this idea goes, I think I'll take a closer look at how animators are currently doing acrobatic movements like this. My goal is to create a rig which streamlines the process. Consider this my first step.