First thing that comes to mind is Frank's online JCS clone thingy for LMAT. A toolbox version of JCS could come in handy for that; ability to open images as maskless tilesets. Also, I think the tileset manager/compiler needs some work. Probably a built-in tileset editor/decompiler as well. Aside from the obvious interface flaws, it should have the ability to convert 1.24 to 1.23 as well.

I actually think it is a good idea. But this is a somewhat biased opinion since I am more interested in creating it than actually using it.