New WAD Tool
From DoomWiki.org
New WAD Tool (NWT) is a DOS WAD editor for Doom, Doom II, and Heretic, created by Denis Moeller of The Innocent Crew in 1996. Much like DeuTex, it can be used to add, edit, and replace lumps inside a WAD file. NWT also has the capability to edit TEXTURE1 and TEXTURE2 and PNAMES lumps, view graphics, listen to sound resources and clean WAD files (much like Cleanwad).
Screenshots
NWT "pro" v1.4
Parallel IWAD/PWAD views, with DOOM2.WAD on the left and DECA.WAD on the right.