Citizens is an NPC plugin in the vein of the old hey0 ones, aimed at creating NPCs that perform a variety of tasks. It adds various NPC types, from simple NPCs that talk to lively, active Guards. Originally featuring only one type of NPC, Citizens now contains 7 toggleable types and 1 creature type. With the Citizens API, plugins developers can make their plugins compatible with NPCs. Server admins are even able to choose which types that they want on their server.
Official URL : http://dev.bukkit.org/server-mods/citizens/
Servers using Citizens, page 16Servers: 360