The old adventure games, like the Monkey Island, Simon the Sorcerer and Indiana Jones series.
More old stuff in general, like the Commander Keen & Jill of the Jungle games.
Fury3 and/or Terminal Velocity
+1 Might and Magic.
The old Elder Scrolls games (I'm sure they were mentioned already, just adding my vote).
The Ultima games would be sweet, although I think the Underworlds had some kind of licensing issues?
That's all off the top of my head....
EDIT: +1 Dungeon Keeper, and also The Incredible Machine games
EDIT2: +1 to The Settlers series! (mainly #2 for me)
Post edited September 23, 2008 by Nebby