Doom Construction Kit v1.0 by Ben Morris.
The ultimate DOOM map editor.  Edit/create
maps faster than you've ever done it before.
Features drag-n-drop, cut-and-paste, button
bars, full menu system and dialog boxes,
online help, and much more.  DCK's tools are
"intelligent", making editing extremely simple
and quick. Requires a node builder (BSP
recommended), a 386+, a mouse, and registered
DOOM.  Uncrippled donateware by Zerius
Development.