Its pretty easy to add new stuff just make a new subclass and make sure to implement 3 methods, then add a button to the right side for it. Its on my maya scripts bitbucket as blendshapetoolkit.py
The things the tool does are.
The first part I wrote because I wanted my blendshapes to keep the cylindrical nature of the helmet.
It has the option to select only the verts that I want to affect
In order to keep things organized it moves the newly created shape to the next spot.
Put a new material on the object with the option to only affect certain faces
For symmetrical meshes mirrors the shape node and moves it to -x
Adds the shape to the blendshape node of the target object
not shown in the video are the ability to rearrange the order and to save and load the list.