WIRED ON FRIDAY: The shop opens in the middle of the night and only sells one product line. When the stock of that product - usually just a few hundred items - is sold out, the shop shuts its doors. Its customers have no prior knowledge about what it will sell. They have to sit and wait until midnight.

And if they miss the sale or it's not what they wanted, well, there'll be another mystery sale along tomorrow. The shop is called Woot and has thousands of very satisfied customers.

The trick is, of course, that Woot is an online store. The mystery goods it sells are bargain-basement tech equipment and gadgets. One day it might be half-price laptops, another time robot pet dogs. Occasionally, it's a $1 (€0.75) "Bag O' Crap", filled with mystery items.

The midnight opening time and odd mix of goods dissuades no one: Woot fans sit with their browsers at midnight to see what cut-price goodies are being sold. Then they stay to chat in its forums: discussing how to use the products they've bought and making suggestions for new products. In the morning, the remaining stock is bought up by visitors who check out Woot over their cornflakes.

"It was meant to be a hobby," admits Woot's creator, Mr Matt Rutledge, who began the site as a spin-off part of his wholesale tech warehouse in Dallas, Texas. Mr Rutledge and his employees spend a lot of time online and they wanted to do something interesting with the woot.com domain they'd bought ("Woot!" is decade-old Net vernacular for generic delight).

Mr Rutledge eventually hit upon the idea of doing a daily deal. "We saw it as a way of getting rid of the leftovers we couldn't sell to dealers," he says.

The site was deliberately designed to be have low overheads. "We created it so that we'd have the least amount of work to do," he says.

One item means no one having to run around the warehouse putting orders together. The forums run themselves.

And Woot's return policy, according to Mr Rutledge, is: "If you're not happy, sell it on eBay."

Woot is now rather more than a hobby. The site has a daily average of 100,000 visitors. Mr Rutledge estimates Woot's annual gross revenues to be around $5 to $10 million - around a third of his total annual revenues for his warehouse business. And all of that came in just five months from launch, with almost no advertising.

Small scale and simple in execution, Woot's simple idea conceals a lot of smart thinking. By selling only one item and shifting from product to product, Mr Rutledge avoids competing with the retailer customers of his main wholesale business. Prices for Woot deals disappear after 24 hours so manufacturers approach him to sell off excess inventory at cut prices without worrying about competing with current stock.

The site's success has largely come from links on weblogs, including a short promotional run on gizmo blog engadget.com. It also exploits the current rise of Really Simple Syndication (RSS) feeds - a Web service that many geeks use to keep up to date with blogs, and now Woot deals, without having to constantly check the site.

RSS subscribers are a captive audience for Mr Rutledge: they'll see his deals every morning with the rest of their online reading.

Offering an RSS feed was a suggestion from one of the forum members - as is Woot's latest innovation, "Woot off", a quick mystery sale that runs immediately after the midnight goodies have been bought up.

Perhaps the biggest surprise of Woot, however, is that no one else is doing anything like this online. In a furiously competitive e-commerce sector, Mr Rutledge finds his company transformed from a small Texan warehouse operation into a site with a brand comparable to Yahoo Stores and Amazon.

So far, it's scaled well, and Mr Rutledge plans more additions in the new year.

But there's one sting in the tail: Woot hasn't worked out how to deliver to Ireland.

"The backend is only designed to take $5 shipping, and we can't reach that far on that."

He says that they're looking into fixing international shipping soon. He better be quick. Given the brilliant simplicity of his idea, Woot may reach these shores, only to be greeted by some cheery European clones.