In the context of computer-based auctions, innovations in proxy bids and auction formats are disclosed. In accordance with the illustrative embodiment, a bidder can program a data processing system to enter one or more bids by proxy. The capabilities offered by the data processing system include: determining one or more bid variables based, at least in part, on the identity of one or more bidders in an auction, or determining one or more bid variables based, at least in part, on the absence of one or more bidders from an auction, or determining one or more bid variables based, at least in part, on the bid variables in one or more other bids, or determining one or more bid variables based, at least in part, on the results of another auction, or determining one or more bid variables based, at least in part, on default values, or waiting a specific or random amount of time before entering a bid in behalf of a bidder, or any combination of these.