Yet, ironically, argues Paul Knegten, head of marketing at Dapper, most of the ads online consumers see, especially "retargeted" ones, are delivered, if you will in the "rear-view mirror," reflecting yesterday's news.

"There are many verticals where real-time information about advertiser inventory can be far better leveraged," says Knegten. "Think of tickets to concerts and other events, where timely offers for an upcoming concert can show updated information about the availability of certain seats. Those kind of data can be used to create really actionable offers."

As a prime example of the opportunities, and current limits, of retargeting, Knegten cites the travel vertical, where dynamic inventory is constantly in flux, with the pricing and availability of seats on flights changing every minute of every day.

"The kind of retargeting we normally see completely fails to reflect that dynamism," he says. "If someone is shopping for a flight from LA to Las Vegas, for instance, the way retargeting currently works is, they'll get some generic ad telling them about 'Flights from $99' out of their origin destination to certain cities they may or may not be interested in.

"This example epitomizes what traditional retargeting means to advertisers: a rotating series of essentially static messages," Knegten adds. " That misses the real story, which is that once you've identified intent, you need to truly seize the moment by radically refocusing the pitch."

"Seizing the moment" requires learning how to better leverage real-time data to communicate urgency.

Dapper's recently launched dynamic remessaging solution is the latest attempt to provide a platform to seize the moment by making the ad (via an XML feed ) pull out data from the advertiser's Web site in real-time. Ads are created dynamically by drawing on already existing creative elements pulled from a marketer's own Web site, from product inventory data, or any kind of informational database.

"What that means," explains Knegten, "is there's a nearly limitless number of creative units produced in an instant to have the most appeal to any particular individual. So, for example, once a cookie indicates a user has looked at a flight from L.A. to Las Vegas, we can pull in the correct product and compellingly timely offers based on real-time price and availability of flights to Las Vegas. Instead of just repeating the same ad about 'Flights to Las Vegas from $99,' we can tell the consumer who was looking for that flight 15 or 20 minutes ago that now there are only four seats left on the flight. Or that if they book NOW they'll get a 20% discount. Real time is what the Web is all about now -- why shouldn't the ads reflect that?"

In a test run this winter on a major travel publishers' site, a hotel chain found that using relevant, timely data on available hotels and pricing greatly boosted performance, outperforming the hotel chain's "best ad" in every placement, and boosting click-through by 253%.

Going forward, Knegten also sees rich possibilities for more granular segmentation using real-time dynamic retargeting. "The cool thing is that we can really map meaningful elements of the page the person looked at, such as prices, product categories, ratings, and so on," he says. "So there's a whole range of possibilities for very rich segmentation based simply on the unique way each user uses the page. So if someone is looking at a five-star hotel in Miami, we can capture that rating and classify it so that business rules can determine that that person is also a high-intent prospect for good deal on a first-class or business-class seat on a flight to Miami that day. The applicability of dynamic remessaging also extends into up-selling related offers. If you looked at that flight from L.A. to Las Vegas we talked about earlier, you could get a follow-on offer that if you book that flight NOW, you can get a special offer for a hotel and flight bundled together."

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