I was thinking about a new building type with a potential to provide more options for the player to acquire needed resources: a Trading Post. As I currently imagine it, this could be implemented as a neutral object on the map, situated in a random location. The trade system could be barter-based to keep it nice and simple - the player could select which resources to exchange and assign villagers to carry the stuff to the Trading Post and back to camp. This behaviour could be paired with other plans and ideas I've been seeing popping up in the threads about convoys with guards around for protection.
To make things more interesting, the new building could perhaps be run by a Merchant, who is a special type of "mob". He could enter the map from time to time, wander around a bit, then choose a location and set up shop. After awhile, he could dismantle the Trading Post and go on his way only to appear again at a later time.