As the world gets older, it seems that nearly all large villages are fully self-contained industries. I don't see any large-scale trade deals, like "We give you cheese, you supply us with metal." providing villages a similar mechanic to realm buffs would make villages be able to specialize in certain areas, but by including negative debuffs in other industries, it could increase large-scale trade interactions between villages. I think a lot about Heroes of Might and Magic 3 cities while playing H&H, and how they look dramatically different from each other, and have unique pros/cons.
Some trivial examples just for the idea:
"Heavily Industrialized" - Bonus to smithed materials and smelted metals.
- Crops grow 50% slower here. Livestock and Trees are less likely to see quality improvement.
"Tree shepards" - Bonus to tree quality improvement and growth. Reduced stunting chance.
- Several similar miserable debuffs
"Prarie Folk" - Bonus to crop stuff
- Several similar miserable debuffs
You could even have the buff system in a credo-like tree, where the further you push down a particular path gives better specialty bonuses (and debuffs). Further down the tree would result in more specific bonuses and deficits. (+5% to wine quality, -50% to breathing)
One huge problem would be village idol spam, just to have multiple separate "villages" to get all the bonuses, under one real village. Increase minimum range or make buffs cost a significant amount might help.
Necropolis: Bonus to LP, -90% HHP, Nature decays.