I'd love this to become even more competitive. How about this scenario: You find an item you like, but it's already been placed into someone else's cart. You then have the opportunity to challenge them for the right to purchase it. In Gilt's case, that challenge could be in the form of a fast-paced fashion quiz, where you have to correctly identify the designers of a certain set of pieces (perhaps from that day's set of available inventory). You wouldn't want to scare off newbies, so you'd need to have the right incentives to play, including discounts on future purchases if you lose, a limited number of "deny this challenge" (get out of jail free) chits, etc.
via www.sippey.com
Translating the Barney's Warehouse free-for-all into an online experience. I like the insta quiz idea..