I ran across a small blip over at Internet Retailer talking about an offer from shoe and handbag site Endless.com regarding shipping.  But the wording at Internet Retailer was a little less than clear so I had to go to the source.  From Endless.com:

From now through February 28th Overnight Shipping is *negative* $5. That's right, until 11:59 p.m. EST February 28th we'll take five dollars off your order for the privilege of shipping overnight to you. We are serious. Enjoy the special promotion–starting on March 1st you can again enjoy our day-in and day-out offer of FREE Overnight Shipping.

So not only does Endless.com, an Amazon company, offer free overnight shipping, but for the entire month of February they'll actually pay you $5 to ship overnight.  Wow!  That's a great way to stir up buzz.  Buzz brings in new traffic.  And with free overnight shipping (or -$5 overnight shipping during February) they've all but ruled out the need to shop locally for shoes and handbags… unless, of course, you're having a fashion emergency that requires instant gratification:

We know how hard it is to wait when you buy something online, so all of the items we sell will be shipped overnight. Yes, it sounds too good to be true, but all orders placed Monday through Friday before 7:30 p.m. EST will ship out that same day for arrival the next business day. (Orders placed after 7:30 p.m. EST Friday and before 7:30 p.m. EST Monday will ship Monday for arrival on Tuesday.) Check the countdown clock on the top of every page for order deadlines and delivery dates. 

Now that's an offer that's hard to refuse!  And the inclusion of the countdown timer (pictured) adds even more buzz and a sense of urgency.  That sense of urgency is great marketing and drives a lot of people to make purchases.  Even if someone isn't sure that they're going to spend money you can make them feel like they're on a deadline - that something great is about to end.  When people think they're missing out or about to run out of time, they spend money.

It's a little bit of psychological marketing.  And it works!