I ran an auction board for a short period of time, and the idea of a "reverse auction" just intrigued me. What this could be used for is in the case of someone posting a "Wanted" item and prospective buyers could bid on offering to sell this item or service to the person looking for it. In this case, however, the bidders would be bidding LOWER prices in order to win the auction. In other words, sellers would be offering the item at the lowest price they could via the bidding process, and the person who posted the "wanted" could wait to see who offered the lowest price on what they are looking for.
Just a thought....