I like the idea of a "Green Grocer" or make it a roadside stand for fruits, veggies and honey (oh my, I'm not believing I said that!) .
I think a Tool shop would be nice, except instead of a visitor asking for tools, we could store our tools there for a price in coins. It could free up barn space, and give us something to spend coins on. (I'm sure this isn't happening).
One other idea would be a school, where snacks would be served, or there could be a "mini-puzzle" to solve.

