This plugin allows you to open a villager's inventory just like any other container in Minecraft.
There is also an option to have villagers drop all their items on death.
When VillagerInv is enabled via /npcinv enable, you can open a villager's inventory by using interact (right mouse button).
Commands:
/npcinv <enable|disable>
Permissions:
npcinv.use - allows players to enable inventory viewing with the command npcinv.edit - allows players to edit the inventory of the villager
Config file
npc-drop-on-death: false
When set to true, villagers will drop their inventory contents on the ground when they die. Note: plugin must be reloaded for changes to config.yml to take place.
Source code available here.
