By Raj Choudhury

Distressed inventory in the travel business is the unsold hotel rooms and airplane seats that become available at the last minute on travel Web sites at fire-sale prices.

But a hotel manager in the near future could be relying on a proximity-based bidding network to convert a cancellation into a booking.

Today, travel brands typically attract consumers to peruse these bargain-priced goodies by dumping them on a travel portal -- hotwire.com, priceline.com, Orbitz -- or by sending promotional emails and text alerts to email addresses and mobile phones.

Yet a proximity-based marketing network could advertise discounted rooms to travelers driving along the interstate when they are just miles from the property. Room offers could be dispatched to car navigation systems and trigger an alert on the screen.

Road warriors who need a place to stay between sales calls and like the price can follow directions on their Garmin or TomTom to speed-dial on their mobile phones and book a room.

Hotel loyalty card members -- Priority Card, Starwood -- can pre-set preferences for room types and price these holds based on when they are travelling in order to get approved text, email, phone or OnStar alerts.

The technology to pull off this transaction hasn't been implemented yet. But the transformational marketing power of proximity-based apps is coming and it will move people to take action.

One form of this advance already is operating in Japan and was exported recently to the United States.

The company, AdLocal, pushes messages to the GPS-enabled and 3G mobile phones of people who have opted into the network.

Retailers and restaurant operators sign up for the channel that sends ads and digital coupons whenever the handsets of consumer subscribers are within four kilometers of their business.

Advertisers also can choose to send mobile messages when subscribers are near the address of a competitor or in a neighborhood they want to target.

Proximity-based applications are spreading. For some time now, fans of social networks have been loading apps to their phones that broadcast their location and messages to friends, who were pre-registered or pre-invited to participate, when they are nearby.

Technophiles are synchronizing their home and office computers with mobile phones through free apps downloaded from the Web.

One called Home Zone enables password entry and calls up a screen saver when the user walks away with his or her phone from the Mac computer. When the user and phone return, the app disables password entry and stops the screen saver.

Home Zone also enables people to set up the software to play iTunes selections, preset the volume, open files and activate the networks their computer taps into just by coming and going with their phone.

We carry our phones almost everywhere. So it's plausible to imagine carmakers contemplating a Bluetooth proximity app that starts a car as its driver approaches the vehicle. How about home security systems that automatically turn on the house lights and deactivate alarm systems as returning homeowners walk toward their front door?

So why not a marketing channel that engages people when they are near your business but too far away to see the signs posted on your storefront?

You can bet there is a horse race underway between the Web portals, geo-targeting agencies, wireless networks, handset providers and many others to deliver the Holy Grail of locally targeted advertising and fulfillment.

Raj Choudhury is Atlanta-based vice president of digital services at Engauge Digital. Reach him at .