Being able to set [BUY] setting in WebAuction, so if you seek something, or want to sell something quick, it would be cool if players could make an offer on the auctions where they buy instead of selling.
On the stock market there are buy and sell orders. A sell order (a simple one) contains a quantity, a desired price, and an expiration date. A buy order contains a quantity, a desired price, and an expiration date. The trick is matching up the two. I really can't sufficiently emphasize what a fantastic idea this is.