After nosing through the novels again, I have a few notes on nickers for the Half-Continent.
In Factotum (chapter 16), Europe and Rossamünd encounter a creature that could be straight out of a Lovecraft plot - a creature that is fairly amorphous and can reshape itself, even divide into smaller yet independent units. And in chapter 22, there is mention of a 'pillboy' (pillbug) nicker and also one that is more akin to a treant.
During the fight for Wormstool in Lamplighter, some are described as bulbous and pudgy, while some are thin and lithe, and another has the legs of an enormous rabbit.
All of these are in addition to the beastman types that seem to be the most common.
So, in general, a wide variety of monster archetypes exist. In my personal opinion, I would stay away from those minis equipped with armor and weapons, although some do use them. The ettin in Lamplighter is using a lamppost for battering the walls of the outpost and he is wearing a small, two-wheeled cart on his head for protection!
A good example of nickers can be seen at this post at Lamplighter's Haven.