Yeah we had a Vendor that you could put up; like a Trade Hub in MO; was nice actually (went it wasnt bug ridded); You could put up what you wanted for each items; up to 12 items.
I however did most of my sales on IRC when I was online...
I enjoyed the hell out of this mechanic in SWG. Make a house or tent, setup a vendor, and sell your wares to any passersby. Im not too hip on a central trading hub though. Typically that just becomes a huge LAGGfest.
Central Trade Hubs wont work, but stands in villages that could become tradehubs could be possible.
Stands which have to have people behind em to be active