A new style of 'free trading' where ANY avatar can rent a pitch for, say 1 hour. After having a pitch, you couldn't have another one for another hour. When you get a pitch, you can spread out up to 10 items, and run it like a mini shop; your items are protected and can only be purchased, not picked up. When your time expires, all unsold items are returned to your inventory. I must admit this is based on nexus's 'drop trading' idea, but maybe subtly different.
I've seen this idea raised in various forms a few times. It's an excellent idea, and MA should do it.