This is one of the most brilliant hacks I've ever seen.
Every day at noon Gilt releases daily price cuts on luxury goods. Due to high demand, many of these sale items become unavailable almost immediately. However, Gilt gives buyers up to ten minutes to decide whether they will pull the trigger and complete the purchase. It is at this point that our hack, a bookmarklet called "Gilt-ii", allows those who have the items in their carts to transform into risk-free auctioneers, selling items to the unlucky people who now gaze upon a "Sold Out - Item in Members' Carts" message.
When a user running "Gilt-ii" opens their shopping cart, their items are automatically registered for auction and displayed to out of luck buyers in the "Gilt-ii Auctions" box right into the item details page.
From the auctions box, buyers submit bids on their desired items. As bids are made, they are displayed to the auctioneers right inside their shopping cart — if they see a price that they like, they can accept the bid and Gilt-ii will automatically handle the money transfer between users and change the shipping information at check out to that of the bidder. Auctioneers spend nothing until someone agrees to purchase the item from them.
A bookmarklet implementation with tight Gilt integration was chosen to enable faster prototype development, but we see this as more of a platform than a site-specific offering. Some places we're thinking about tackling next are OpenTable for restaurant reservations and sites like Ticketmaster for event sales.