Have you ever wondered how many transactions take place on eBay during the biggest shopping days of the year? Find the answer—and get deals, prizes and streamlined shopping—with these recent developments by eBay.

Along with sexy vampires and Michelle Obama arms, flash sales are all the rage these days. Websites like Gilt, Rue La La, Hautelook and several others specialize in limited-time-only ("flash") sales of new, name brand merchandise, often to a members-only group of customers. It's a concept that's perfectly timed for the current economy: Consumers are not just eager, but practically expect to get a discount these days; and manufacturers, saddled with too much inventory and fewer and fewer outlets to sell it through, are more than willing to partner with outlets that specialize in liquidating their warehouses. The fact that inventory is limited and the sales typically last for only two or three days adds an extra layer of excitement—and added motivation for the customer to make an impulse purchase, lest the item be gone the next time you log in.

It seems only fitting that eBay, the largest online marketplace in the world and the best place pretty much ever to get a great deal on anything, would launch a flash sale site of its own. In mid-November, eBay's own Fashion Vault launched with sales of Cole Haan and Hugo Boss.

Today through December 3rd at 8am, DKNY Women's Apparel and Accessories will be featured on the site, with prices up to 60 percent off retail. I've gotten a sneak peak at what's on tap, and there's a houndstooth pencil skirt I'll be virtually lining up for before the sale begins at 8am.

Next up, Max Mara & Marina Rinaldi from Dec 7th through December 10th.

eBay Fashion Vault Sale: DKNY Women's Apparel and Accessories
Up to 60% OFF
Free Shipping
Three Days Only: November 30th at 8am through December 3rd at 8am

In other eBay news: How cool is this?! eBay's animated holiday shopping map shows exactly how many people shopped on eBay on Black Friday, the traditional beginning of the holiday shopping season. The visualization shows which areas of the country were responsible for the site's 1,027,807 buyer seller transations on that day. If you have time in between making your own holiday shopping purchases, check back after Cyber Monday(today!) for a new version of the map.

I'm a little bit obsessed with Norma Kamali's All In One Tunic. Part of the designer's exclusive eBay collection, the $60 fashion wonder, designed in a chic, skinny black and white stripe, can be worn in countless ways: a one shoulder boat neck, a one shoulder strapless dress, a halter dress, a side tie skirt, and more. For folks who, according to Kamali, "fancy themselves fashion stylists," here's a chance to win a $500 gift certificate on Kamali's website: Just post photos of your self on Kamali's Facebook fan page showing how many ways you styled the tunic. The winner will be chosen by Kamali herself. Click here for details.

Finally, two new announcements from the world of eBay mobile apps: The upgrade to the eBay on iPhone app lets you shop eBay from wherever you are, complete with new updates including a "best offer" feature that lets mobile shoppers instantly negotiate prices directly with sellers, a "push to talk" customer service feature, and social networking integration that lets you share your shopping scores with your friends. The brand new daily deals app features limited quantity items from trusted sellers at deep discounts, and with free shipping. These auction items have zero bids and less than four hours of listing time remaining, so you're likely to have sellers willing to make a serious deal.