Honestly, I'd kill for some sort of actual system for selling and buying things. Posting a list of what you have in gamn these boards is all well and good, but not all of us have every single item in the game memorized simply by name. Most of us need to actually LOOK at the items to determine if we want to spend hard-earned coin on them or not. And, as was pointed out, laying things on the ground is time-consuming, lag-inducing, and, despite the wonderful shopping opportunity it presents, probably against any sort of actual common sense in the outskirts (varja everywhere! Oh my!).
Some sort of "temporary merchant stall" that allowed you to put items in that people could walk up and inspect like a merchant's goods would be wonderful. Make it so only the person who put the items in could remove them, then people could come up, inspect the inventory, and haggle with the merchant. When a deal was made, the merchant grabs the item out of the "stall inventory" and sells it. Man, that would be sweet.