Entering a dungeon and just running in and fighting the enemies right away can get a tad boring at times, and you can only use the old "guess the password" or "find the key" gimmicks so often. Here I intend that we share ideas for interesting security mechanisms that more intelligent enemies might have placed in their lairs and dungeons.
I'll start off; This one is awfully simple, really. In a special pop-up decision-box dealie(like what happens when you walk up to a turnable wheel that opens gates, you get a choice between turning it and leaving it alone.) should pop up when you enter the room that has the control levers in it. Your Brave Adventurers would have to choose the correct sequence to pull the levers(or other things) from choices presented in the choice-box. It would probably be best that you give the player fair warning that a trap could be sprung on them if they choose the wrong sequence, like saying "There are suspicious little holes in the floor here" (the old spike shooting-up trap). It would be good if there were some way to find the proper sequence, as well, like how you can find maps and passwords and things off of people in some of the Avernum games. If they choose the wrong sequence anyway, you get to describe their grisly death by the trap, or you could simply have a bunch of enemies waltz in and attack, if you want to give the player a chance to escape.
It's the sort of thing you COULD get right after a few reloads, so I guess it's not very good, but I'm sure that you all can think of better ones.