Flat surface deformer

We all know, that rigid boxes, almost regardless of any material are never a perfectly shaped 3d objects, their sides/faces are very often slightly distorted, so it would be very nice to have a option to define a parameter for distorting a plane side. I would see it similar to the object class like we have it now with "bottom". So for example one would put a shape that would pull outside or push inside the plane area it sits on. Object size and shape would define area affected by distortion, together with a threshold parameter. So for example a simple cube box would get a very nice organic finish by slightly curved sides.