When Doom 3 was in development, Trent Reznor of Nine Inch Nails was hired to create sounds for the game, but later he quit the job, for reasons unknown to me. Before he quit, he already created a lot of sounds which were used in the leaked Doom 3 Alpha, but none of them were used in the final game. Later, an unofficial mod for Doom 3 with Trent's sounds surfaced. The mod replaces sounds for the player, the imp, the hellknight, the chaingun, the machine gun, and the pistol. Although the file description says the shotgun sounds are replaced too, only the "dry" click sounds are replaced, not the firing sounds.
Now I created a WAD that replaces the original Doom/Doom2 player sounds with those by Trent. There are at least 5 new sounds for each original sound, all are played at random. There are 6 new jump sounds for those who switched on ZDoom's jump ability. Trent also recorded 57(!) pain sounds for different "amounts" of pain. Fortunately the ZDoom programmers had the foresight to create 4 different pain sound states depending on how much damage the player takes, so I distributed the sounds among those states.
I also made a WAD that replaces the pistol and chaingun sounds, but I guess I'll use these sounds for new weapons instead.