Similar to the new warp tool in the 3d view it would be super effective to have a way to do that in the 2d view, similar to what photoshop does. I find myself switching over to photoshop to do this currently for clothing seams when I want things to ride along the edge of a uv island. I feel like the tools are already there they could just be added to the 2d view. I'm assuming its not that simple but really think this would be a very solid tool.
Ive tried doing this with the current warp filter but its just too hard to control and with a gradient and is very limited in functionality.