WhaBam, an online auction site launched over the summer, said it offers a reverse auctions feature. If shoppers cannot find items they are looking for, they can list an item in a reverse auction with the price they're willing to pay, and have sellers bid for their business. This allows buyers to pick and choose the sellers they want to work with, and creates a new sales channel for sellers.

Buyers create a listing giving the name of the item wanted, a description, the maximum amount they would be willing to pay for the item, categories, and images. They can also specify an ending time. WhaBam has an internal mail system that enables buyers and sellers to communicate directly regarding auction items.

http://www.whabam.com