As many talkative cab drivers know, customers have little choice but to hear them out. Now Madison Avenue is aiming its pitch at the same backseat captives. When they step into New York City taxis these days, passengers may find themselves facing electronic signboards that tout everything from beer to Broadway shows. The computerized messages march in inch-high letters across the boards, which are set atop a glass partition between driver and rider. Each 10-sec. plug is part of a cycle that includes public service notices and trivia questions for variety, and repeats itself every four minutes.
Called Taxigrams, the...