Adidas, for instance, with its agency partner iProspect, determined that including the real value of a click on a store locator button, which it had identified from store data, proved that mobile ads were paying off in in-store sales.

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Rather than fill the device with bloatware apps or overlay a custom UI, Sprint's installed a software button that takes you to a store exclusively designed for Sprint's new Android devices.

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As well as keys representing the standard Android commands, the console also sports a "shield" button that takes users to a curated games store featuring titles selected from the Google Play marketplace.

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It returned to the store a few days later after adding an in-app button to let users alert the service to inappropriate pictures.

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Rather than force its customers to chase down sales help, Lowe's has a call button in most aisles to bring the employee to you (a store manager's bonus depends, in part, on how often help arrives within 60 seconds).

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"Everyone wants a button to have a piece of the day, " Marketing Merchandising Director Meaghan Burdick said at the store's sneak peek this week.

CNN: January 18, 2013 -- Updated 2151 GMT (0551 HKT)