Some pointers on fast but pretty good reviews of old IdTech and their adaptions to iPhone!
Ah those good old days... I was so young when I played Doom the first time on a friend's computer. By the way, everyone should read Micheal Abrash's Black Book full of anecdotes and in-depth details about Quake renderer algorithms. For instance, you would learn that John Carmack bet that he could implement dynamic lighting in the quake engine in less than an hour. Indeed, he failed but of only few minutes (3 to 7, I can't remember). But hell yeah! In an hour! :)