DOOM 2: Codes

iddt       : Use on map screen, type several times
             Shows full map, then shows location of all objects, then erases
iddqd      : God mode
idkfa      : Full ammo + 200% armor, no backpack (Kick Fuckin' Ass)
idclip     : No clipping
idbehold   : Followed by R, I, V, A, L, or S
             R = Radiation suit
             I = Invisible
             V = Invincible
             A = Automap (reveal entire map)
             L = Light amplification
             S = Berserker mode
idclev     : Followed by map number (a warp!)
idmypos    : Prints your coordinates in hex
idchoppers : Prints "Doesn't suck - GM" and gives you a chainsaw and makes you
             invincible.
idmus      : Followed by map number (plays music from selected level)