I like the idea of guards; to protect against mobs, and to hostile players if they destroy any naturally occurring blocks in the radius of the town, steal from chests, attack village npcs, harvest village cops, etc.
Reminds me of the NPCs in the Citizens plugin where you can arm them and tell them to patrol and stuff. I think the villagers should also arm themselves with low-end weapons like wood swords and stone axes.
My idea is that if you build a gravel road out of a big enough town, a group of villagers and an Iron Golem walk down it. They'd either start a new town at the end of the road, at the nearest possible spot, or whenever the sun goes down. Then villagers and Iron Golems walk back and forth randomly in the daytime, villagers for population things & putting torches/lamps on the sides to prevent mobs and Iron Golems for guarding.