I noticed an empty space under the Sculpt Image preview and thought I'd take the chance to suggest some new object features. I admit that i'm not much of a programmer but have tried to keep this as realistic as I can.
I think a very importent feature would be a flip option on each axis. If I decide to model a shoe, I don't much like the idea of uploading a second set of images for the other foot. Another could be an invert option, although this can be mended with an simple image flip.
My last suggestion could be a little more differcult. a number value that would expand/contract the resulting mesh by it's face normals. This could have many uses but the one I have in mind is to layer different maps for special effects without Z-fight.
I hope these ideas are possible and will be considered.