DoomCenter E1 Mapping Contest (E1CONTEST.WAD)

Doom Center was an important fixture of the community during the post-source port boom. It was something of a media hub in its promotion of PWADs and their authors. It eventually deactivated with the death of its host but some of its staff went on to join Doomworld. Snapshots of the site were thankfully preserved via archive.org but most of its content and enthusiasm have not figured into its legacy. I only know of Doom Center's existence because it hosted a map-making contest during a week that celebrated the shareware episode in 2001. John Romero himself judged the submissions; the winner received an autographed copy of the Ultimate Doom.

Visions of Eternity (VOE.WAD)

You may not be familiar with the name Tobias Münch, but Pablo Dictter might ring a bell. The two are partners in crime, coming together to bang out the lesser-profile Doom II episode Hatomo Battles the Yomi Demons in 2007. This isn't a joint venture, though; Tobias made Visions of Eternity all by his lonesome, releasing it in late 2013. It's a single episode for the original Doom, but plays in ZDoom. The only caveat is that I see very few reasons why Tobias picked the engine since he doesn't go wild with the detailing, the main one being its presence on the menu as a fifth episode.