Have you ever wondered where Zombie Pigmen come from? Well, their name implies that there are regular Pigmen in the Nether too. Pigmen would be a neutral mob that spawns in the Nether. You would find groups of these Pigmen in Nether Towns, or find a lone adventurer in a Nether Fortress. In your average Nether town, there are going to be 5 or 6 Pigmen.
There will be 4 building types, Regular, Farm, Blacksmith, and Church. The regular houses can come in many forms. the Farm will contain carrots and Nether Warts. the Blacksmith will have a Stonecutter (once it is fully implemented), Furnaces, and an Anvil. Blacksmith chests will contain Iron, Quartz, and sometimes Ghast tears. The church is where the Brewing happens. There will be 2 Brewing Stands. Sometimes, there will be potions of Fire Resistance or Healing in the Stands. Bells (when fully implemented) will be placed on the ceiling, and there will be carpets on the floor. It is a Church after all.
When a Zombie Pigman is attacked, Any nearby Pigmen will become angry as well. They will take out Stone or Iron Swords and start attacking. When more then 3 Pigmen die, the rest will flee. They will drop porkchops, Nether Warts, and carrots. They have a small chance of dropping their weapon.
When brought to the Overworld, they will be confused. They will make loud pig sounds for a few seconds, then calm down. If a group of Pigmen find a Zombie Village, they will take out the Zombies and inhabit the Village.
A Pigman can be traded with like a Villiger. They don't really have professions. You can trade Gold for potions, Nether Wart, or carrots, or the other way around.
If a Pigman sees a Zombie Pigman, they will try and lure it to the church where it can be cured. This is the only way a Zombie Pigman can be cured. If the Town's population is too high, the Pigman will ignore its deceased friend.
If a Pigman sees a pig, it will follow it for a while. If you kill the pig, the Pigman will attack you, thinking that the pig was a Pigman.
Pigmen would add a new aspect to visiting the Nether, making the Nether have another reason to be explored.