The Hessling Editor -- Available from http://hessling-editor.sourceforge.net
A free implementation of the xedit/kedit editor concept(the IBM mainframe style editor, not the X Windows based editor).
Uses REXX as a macro/scripting language.
Has an interesting line/block oriented prefix command area that may be more intuitive than vi's command mode editing commands.
Is (roughly) as extensible as emacs but uses roughly 1/15 the disk space (even less if you don't include the Regina REXX interpreter in the calculations).
Allows muscle memory to be developed for keyboard command sequences allowing rapid editing for power users (similar to power of vi or emacs).
LES: Uses REXX as a macro/scripting language? Why? Why not Tcl? So I suppose it's just got to do with Tk, hasn't it? Because I know a little Rexx and it doesn't stink, but isn't Tcl a lot better?
The primary reason this application appears on this wiki is because of viTHE - the beginning of an attempt to write a Tcl/Tk version of THE.