dude, it's called http://nestgrid.org. Add and rearrange nodes to your heart's content, in a beautiful ui resembling text editor or an IDE.

nestgrid is a general purpose tree editor. Description, in-browser flash demo and desktop app installer are available at http://nestgrid.org

ETA: incidentally, architecturally it is structured for easy plugin / "script" extensibility, like a low key emacs.