I really like the idea of being able to pull other people around. People could provide a "taxi" or "bus" service and charge other players some tria to carry them to different locations. They could even make different routes (for example, start at Hydlaa's north gate, make a stop at the magic shop, the iron mines, gug city, and other points of interest).
Not only would this be convenient and allow more jobs for players to RP, but players riding in the cart would be encouraged to have RP conversations, and it would allow for some fun RP events (for example, a gang of bandits attacking a caravan).
I realize this probably wouldn't be easy to implement. But it'd be a lot of fun.