In the next 30 days, eBay will be enforcing a new policy that will put an end to auction duration extension programs on eBay.   eBay had authorized the license for programs that eBay sellers can pay to use, that automatically extend the duration of their auctions.  So, you could post a one-day listing, and if no bids are placed, the program would automatically extend the duration.  This keeps the listing at the top of the "Ending Soonest" pages for more days.
 
eBay has announced that they now feel this is a form a fee circumvention, and have stated, "Extension of auctions by a seller for any reason is not only a form of fee avoidance, but also harms the finding experience for buyers."
 
Here is the verbiage:
 
"Extension of Auctions - eBay listings ('auctions') have a fixed duration. eBay may on rare occasions (for example, as the result of a site outage) extend the duration of an auction. Extension of auction duration by a seller, via either manual actions or the use of automated tools, is not permitted. Extension of auctions by a seller for any reason is not only a form of fee avoidance, but also harms the finding experience for buyers."
http://pages.ebay.com/help/policies/listing-circumventing.html
 
This new addition to the policy bans automatic extender tools, but it also bans manual revisions of auction durations. Formerly, eBay allowed sellers to change duration in special circumstances. It appears seller will no longer be able to change the listing duration manually, either.  eBay has yet to make a formal announcement to sellers, but has contacted the eBay Certified Solution Providers to inform them that they will begin aggressively enforcing this new policy in the next 30 days.  Keep your eyes open for an announcement!