Out-of-home advertising is rosy, and digital
Out-of-home advertising (including billboards, posters on the tube, ads on street furniture) is predicted to be the fastest growing non-internet form of advertising. From Billboard Boom, The Economist, April 20 2011.
The reason is the switch to digital: "The falling price and improving quality of flat-screen displays mean that static posters printed on paper are being replaced by snazzy digital commercials with moving pictures, sound and sometimes interactive features. As some advertising media, especially newspapers, see their audiences fade, streets, airports and other public spaces are becoming crowded with more potential viewers than ever, as people continue moving to cities and travel more."