Soon you'll be able to skip the box-office line and head straight to your seat by swiping your mobile device over a scanner. It can read the bar code of an electronic ticket purchased with an app that also gives show times, movie reviews and seating information.

Phones in the theater were once regarded as a nuisance, but not anymore-theaters welcome them. Along with better seats, 3-D projectors and upscale snacks, smartphones, iPads and other tablets are changing the century-old exhibition business, presenting opportunity for growth in an industry trying to stay relevant in the digital age.

A new app called MoviePal enables users to store trailers on their cellphones while sitting in the auditorium, and then sends them a reminder when the movie from the tagged trailer is being released.