Auction Sniping

According to Wikipedia;

Auction sniping is the process of watching a timed online auction (such as on eBay), and placing a winning bid at the last possible moment (often seconds before the end of the auction), giving the other bidders no time to outbid the sniper. Some bidders do this manually, and others use software designed for the purpose. A bid sniper is a person or software agent who performs auction sniping.

There are also online sniping services, where the software agent is run from a website rather than the sniper's own computer. This decreases the failure rate of the snipe, because the website is expected to have more reliable servers that might be quicker to react.

Auction Sniping @ Amazon.com