What a fantastic thread, wish Id found it sooner! I absolutely love butt growth, only comes behind(pun intended) breast and height growth. I have some butt growth in my image story " Growing Circle" however I will definitely need to make a nice buttcentric growth scene in the third comic I am working on. Big growing butt with still a small waist is absolute heaven.
This is one of the images from one of the butt growth parts of the story:
http://fav.me/d4jv8wg