Here's a new page, hosted by DoomWadStation, and is dedicated to wads especially made for the GZ Doom port. http://gzdoom.doomwadstation.com/news.html . It's also been added to the links on the Dome Doom2 conversions page. Add-ons - DOOM2.
I saw on somebody’s web site that there’s a secret Wolfenstein level in TUTNT. So I clicked on the link and it went to TUTNT: The Ultimate Torment & Torture: http://www.realm667.com/index.php?option=com_content&task=view&id=289 It requires GZDoom: http://grafzahl.drdteam.org/ I’ve tried following the source port directions on http://www.wolfenstein3d.co.uk/adds_DOOM2.htm , but I get errors. Can somebody please tell me how they’ve loaded it up in GZDoom?