As a seller you can see the high bidders email address at all times..
The 2nd bidder and the winning bidder had the exact same email address which was based on there last name, one was and aol account and the other a charter account.. They also both live in the exact same city. I sent an email to ebay so they could investigate and they suspended both ebay accounts. I received an email from my ebay seller rep saying that not only did he just do this but was using his wife's account to shill bid his own auctions, to drive the price up..