>>5
It's still a hotly debated topic, but eBay has still decided on the hard time limit auction format. I know online auction sites that discourage sniping by extending auctions like you propose do exist, but the only one that immediately comes to mind is the furry commissions auction site FurBid.

>>6
In fact, that's what you're supposed to do anyway. Put in a bid equal to what you're willing to pay, and the server bids up to that amount for you. It bids the smallest amount that'll win the auction for you, even if that smaller amount gets outbid, unless the outbid is more than you put in.