Here is an idea that I was playing with for a little bit. I was planning on putting it into a server that I am a part of, but I wanted to get some more feedback before it goes up.
A zombie can pick up armor or swords, and depending on the type of armor he currently possesses, he can pick up an enchanted item, or a damaged item. This particular zombie picks up enchanted items, and so only enchanted items will be detected by the system. If the item is "trade-able", then the "villager" will offer the player 1 or 3 emerald in return. The player can choose to accept or decline the trade. If accepted, the player will get the emerald, and the system will take the armor/sword. If declined, the system will return the armor/sword, and take the emerald.
A zombie can pick up armor or swords, and depending on the type of armor he currently possesses, he can pick up an enchanted item, or a damaged item. This particular zombie picks up enchanted items, and so only enchanted items will be detected by the system. If the item is "trade-able", then the "villager" will offer the player 1 or 3 emerald in return. The player can choose to accept or decline the trade. If accepted, the player will get the emerald, and the system will take the armor/sword. If declined, the system will return the armor/sword, and take the emerald.
http://www.youtube.com/playlist?list=PLAh7oDLNm5tmkAdg2lemLV0rbsSgHJlAA