Air travelers are a highly desirable audience for advertisers, but airports don't always make it easy to reach them. That's the message I take away from two separate studies on air travelers and out-of-home advertising -- one conducted by Scarborough for Clear Channel Airports, the other by Opinion Research Corporation for NCR Corp., a provider of airline and airport self-service, retail, wayfinding and mobile solutions.

RMG Networks will have two fewer digital out-of-home networks to its name once it completes a planned divestiture of some big assets -- its Fitness network and NYTimes.com network. The sale of these two networks will allow the company to focus on its other DOOH networks, which reach businesspeople as they travel -- including displays in airplanes, airport lounges, taxis, Amtrak trains, and elsewhere -- according to the DailyDOOH blog.

Screenvision, one of two leading cinema advertising companies, is bringing together the silver screen with its smaller, mobile cousins in The Limelight, a new pre-show package of advertising and entertainment whose "two-screen" configuration combines mobile interactivity with the impact of ads seen in movie theaters.

While marketers typically fret about the optimal way to allocate their budgets across different media, when it comes to public safety there's really only one way to go: flood the zone. With that in mind, digital signage software provider Visix has partnered with Rave Mobile Safety, in effect creating a multi-platform safety alert system for college campuses that combines digital out-of-home and mobile channels.

New Yorkers, prepare yourselves for a surge of digital out-of-home video displays in public spaces in the not-too-distant future. This wave of DOOH is coming to New York City courtesy of public agencies and private companies working in tandem.

The nation's largest public transit agency is seeking expressions of interest from potential digital out-of-home advertising partners as part of the Metropolitan Transportation Agency's creation of a network of interactive customer information kiosks, called "On the Go!" Travel Stations.

Subway locations across the world will be joining a digital signage network, called Subway TV & Radio, courtesy of a deal between Real Digital Media and the Independent Purchasing Cooperative, which represents independent Subway franchises.

Patients and their families are a favorite target audience for digital out-of-home video networks, and this week brought a new player in the form of Aceso's Hospital TV Network, or HTV for short. HTV will deliver content focused on healthy lifestyles, entertainment, and learning -- along with targeted advertising -- to hospital common and waiting areas. It functions as an extension of UpCare, a digital video network also operated by Aceso, which engages patients in their hospital rooms.

A new deal is bringing Fox News content to Outcast's PumpTop TV, a digital out-of-home network that delivers video content to displays in gas pumps. The exclusive partnership gives PumpTop TV access to daily news updates from Fox News, which will appear on its network of over 13,000 screens at gas stations nationwide.

OK, in this case the displays themselves aren't digital, but there's a digital component involving mobile interaction -- and the model employed by transit advertising company Titan and Internet emporium Peapod, enabling commuters to do on-the-go grocery shopping, is neat enough to bear a closer look.