Some of Inwindow’s work.

The answer: Get an advertiser to fill up the windows until you find a new tenant.

Today’s Wall Street Journal has an article about malls that are selling their storefronts to advertisers.

Rotten times for retail landlords have added momentum to the emerging industry of in-mall advertising….Vacancy rates at malls and shopping centers this year have hit their highest levels in at least seven years, and vacancies likely will increase next year, according to real-estate research firm Reis Inc. Among the retailers closing stores across the country are chains Linens ‘n Things Inc., Wilson’s the Leather Experts Inc. and Whitehall Jewelers Holdings Inc.

The article cites several companies, start-ups, that are capitalizing on this, including WindowGain Inc, which does “high definition outdoor advertising,” projecting videos onto windows, and Inwindow Outdoor LLC, which stretches high-definition vinyl overlays across windows, and has the somewhat hilarious slogan “THINK Outside the Box, BE Inside the Window.”

How much will it cost you malls of America?

The proposition has little, if any, downside for landlords. Inwindow pays landlords a flat monthly rate of $1,000 to $8,000, depending on the ad’s size and foot traffic passing the site, executives say.