The use of the internet for commerce has spawned a variety of auctions, marketplaces, and exchanges for trading everything from bandwidth to books. Mechanisms for bidding agents, dynamic pricing, and combinatorial bids are being implemented in support of internet-based auctions, giving rise to new versions of optimization and resource allocation models. This volume, a collection of papers from an IMA "Hot Topics" workshop in internet auctions, includes descriptions of real and proposed auctions, complete with mathematical model formulations, theoretical results, solution approaches, and computational studies. This volume also provides a mathematical programming perspective on open questions in auction theory, and provides a glimpse of the growing area of dynamic pricing.