Amazon.com
Not just books anymore, check out the amazon.com auctions.
Bidder's Edge
A free service which allows you to search across many auction sites at once. They provide historical pricing to help you determine if you are getting a good deal, and allow you to monitor ongoing auctions and watch for items in upcoming auctions.
CarScene.com
Powered by car buffs, and fueled by the Internet, this is the place where you can buy, sell, talk and dream specialty cars. Sell your car by auction! They are about to merge with CollectorCarTraderOnline.com.
SportingAuction
An on-line auction of all kinds of sporting goods, from baseball, soccer and basketball to water sports, fishing and camping. Try it out! You might get a great deal!