You can do some pretty amazing stuff with the toolset (at least relative to the game).
I'm even more impressed by how modders achieve these things in roundabout and inventive ways. Like that door that opens with a keyword in chat: It's just a normal key-only locked door with an invisible/untargetable NPC nearby that listens for the required word and walks up and opens the door with they key in his inventory. Or the fact that (not sure if still the case) ridable horses are actually "tails" that attach to the player, just with their own model and animation sets.
A module that stayed in my memory for the non-standard things would be "Demon". The guy made a whole TCG style mini-game in the vein of MTG for it. Then for his NWN2 module there's a guitar hero minigame in it
. Anyway, I suspect if you want to see the limits of what can be done with the toolset (and even "expanded" ones at that) you'd have to visit some more popular PW. Those people have been at it for... well over a decade by now... Often times when content gets put out it had been made for some PW or other first, but then was released separately for the people's enjoyment. Be it models, effects, music, creatures, scripting systems, you name it.