I'm developing a tool to let final user warp bitmaps.
Each deformation is made in real-time just using mouse drag and drop. No grids, no control points. I think it can't be easier or more intuitive. The warping is local, directed, and affect only the region around the mouse (and its path).
I have already made an example to show here. First you see a normal "a". After you see the same letter "a" warped by my model. This second image was created playing a lot with the original image. It's the result of a lot of accumulative warpings made with mouse.
This tool is getting great, but it still need some more improvement and some degree of configuration too. I'm working on it.