Dynamic Creature Lair System
This was in the old module, essentially it was similar to Ravenloft's creature population system where certain creatures would multiply if left unchecked and even establish lairs which could out send raiding parties. Makes the world feel more alive and unscripted; it could even be tied into a creature bounty system of sort which would change depending on what is a threat at any given time. I can see if I can find the script on NWNVault again if need be.

Randomized explorable areas
Makes adventuring even more fun and less predictable.

Merchant Stalls
Allows players to sell their wares even if they aren't online at the time.