I had an idea to put up an auction system under the find interface. Have it setup like ebay, where residents would pay a fee to list an item. You could use the find interface, where you would have an image, and a brief description of the item for sale. I think it'd be quite useful to have something like this. Would also cut down on the "garage sale" events that have been spamming the event board lately.
I proposed a vote on this, prop #533