Yeah, there is a great encounter in the ice spire (or whatever it is called) adventure. Great use of terrain, multiple heights....I've already stolen and used it once as a swamp encounter (though I changed it and made the terrain too effective in a way). I also suggest Dungeon. Every single encounter can be stolen and used in a different setting.
I like encounters where there are multiple levels, like balconies or rocks or ledges or whatever. I like encounters where there is some stuff in the room that the bad guys can hide behind, use for cover, throw at the PCs. I like encounters with pits or other things that make slide/push/pull more interesting (they don't need to be deep, just enough to effect the target's ability to do something). I like terrain that is more than one room, where the combatants can move around...