Tool I created for animators at Rooster Teeth as a means of giving them more control over model deformations and smears. Integrated with our PennyBot system, you can select a vertex on a skinned mesh and run the script, creating a set of controls that will follow the mesh, and can be used to modify the mesh on a shot-by-shot basis.
There are controls for envelope, influence type (volume, or surface), and scale can be used for influence radius. There is the control to move the "smear", and a secondary control to move the origin of the smear on the character.

Somewhat rig and tool creation by me
Animation by Megan Pellino