Gunbroker has it all wrong. Sniping is the best part of online auctions.
I agree 100%. Additionally, that 15 minute rule can really be an inconvenience. Let the damn thing end on time!
Imagine a Christine's or Sotheby's auction conducted along the lines of an eBay snipe:
"The current bid on this lovely Renoir painting is $2,125,000. Do I have any more bids? Anyone? Going... going..."
"I bid $2,125,001!"
"Sold! To this person for $2,125,001!"
Sniping sucks, plain and simple. Especially if the program allows you to bid one penny higher than a honest bid.