I picked up the book Masters of Doom: How Two Guys Created an Empire and Transformed Pop Culture by David Kushner this week while in Columbus.  This is a great book - right up there with The Soul of a New Machine and Show-stopper!.  Having lived through this era (Wolfenstein 3D to Doom to Quake), it is especially nostalgic to recount the impact Carmack and Romero had on our culture.  The first time I ever played Doom deathmatch was actually on an SGI box while working at Wright Labratory for the USAF doing cockpit research.