One more idea to retain from Blizz's new game Diablo3. Object displacement and dungeon rooms are completely random:

http://www.gamespot.com/pc/rpg/diablo3/video/6199524/diablo-iii-interview-5

This is both an incredible idea, and kinda of must have also, for diablo 3 or any game alike, where you may be re-entering the same dungeons multiple times so they will never feel to be repeatedly boring. :)