I think it would be neat to have traveling caravans, entertainment and merchant, that travel between the NPC cities. They can have quests, offer special deals on items and such. Maybe this can be included for player towns, where players can pay to hire a carnival to come to their town. They can supply some or all the prizes for the mini games and earn money and bring new players to their town. An npc in the towns can know of the caravans whereabouts for players to travel to them. For the entertainment a player can be hired to help with the entertainment. Gathering some resources, catch (tame) and animal for them. A player could also pay to enter and enjoy the traveling entertainment. Play some mini games to win a cosmetic prize, a hat, mask or maybe something for the house. The merchant can offer special items/deals. Maybe they have an overstock of one item and sell it slightly cheaper then other vendors. Maybe they need more of an item and offer a slightly better price for it, this would be something not bought from another npc. A player can do a quest to deliver some goods to an npc close by. Go around asking the town where the person is and track them down. Can also have random refuges camp out in a town to seek aid before moving on to a major city to start a new life.
Nothing stopping players from creating their own traveling carnival ... That would be fun actually ... Hmmm.
I think that players should be able to build their own caravan to haul their heavy amounts of loot around the map. Maybe you can occasionally come across a scene where a caravan lost a wheel and you get a quest from the NPC's in the caravan. Or maybe the caravan with the missing wheel has no one in it! Or even worse... the people with the caravan who lost the wheel tell you to deliver a message to someone in town... but being naughty curious despicable you, you look inside their caravan when they aren't looking and inside their treasure chest you find human skulls or shrunken heads and the NPC's are actually undead critters in disguise and your allowing the undead to raid a city by helping them out! =O All kinds of possibilities with them caravans. I'd be the naughty fellow who would discover the shrunken heads in the caravan. =)