Blender has a great feature called a constraint.
You can constrain the movement, scaling, and rotation of an object with one simple menu of constraints.
The existing constrain to layout behaviour could have X+,X-,Y+,and Y- settings so we could define a "play area" . This would be extremely useful for Physics simulations.
During physics simulations I have to put in barriers and boundaries so things do not encroach the GUI area. It would be really cool if I could just put a location constraint on a family of objects instead.
I do not think the Pin behaviour supports rotation or scaling, So a "constrain to parents scale", and "constrain to parents rotation" feature would be really nice.
I have run into a few situations where I did not want a pinned object to rotate with the sprite it is attached to. My solution is to reset the rotation on my sprite every time the parent sprite rotates.
On the flip side I have run into a few situations where I wanted every object in a container to scale or rotate with the parent object. This is useful for special effects and drop shadows.
It seems like every time I am using a container, I have to include little hacks for rotation and scaling.
Well, anyway, with a few tweaks to the existing Pin, and Bound to layout behaviours we could have a nice set of constraint tools.