Development:Final Doom (DOS, Mac OS Classic, PlayStation 3)
This page details development materials of Final Doom (DOS, Mac OS Classic, PlayStation 3).
Pretty much every map. Comparisons between early and final maps. Check for individual difficulty and multiplayer-only settings. Find some here.
Being active members of the Doom Mapping community, TeamTNT and the brothers Casali put out early versions of their final maps, whether as single levels or in compilations.
MAP01: System Control
A version of this can be found in DWANGO6, a Deathmatching compilation, as MAP11. Do note that any music used in DWANGO maps was most likely not meant for the map proper, but was added by the map compiler.
MAP17: Processing Area
Can be found in #1DWANGO (not DWANGO1, that's a different mapset) as MAP06.
The Plutonia Experiment
While a few Plutonia maps were originally meant for TNT and got rejected for their difficulty, that's not the focus (ahem) here.
MAP32: Go 2 It
Two early versions were put out by Dario Casali as standalone maps under the names of Punisher and Punisher 2.