American Airlines and Apple Passbook produce 20,000 boarding passes per day

Apple’s Passbook feature of iOS 6 has become a surprise hit for developers.

Passbook is virtual file folder for all those bits of paper you accumulate in your wallet: tickets, boarding passes, coupons and so forth. The Apple-built app aggregates them from third-party apps like Fandango and Starbucks in one convenient place. Each app gets a pass that then, based upon your GPS location, pops up on the lockscreen to, say, remind you that you’ve got a $50 gift card at Target or nine bucks left on your Starbucks card as you’re walking past the store.

American Airlines and cosmetics retailer Sephora are among the big-name companies that have developed apps for Passbook and seen them downloaded by the tens of thousands since it was announced in June. Passbook also plays nicely with Eventbrite, Ticketmaster and Square. Apple doesn’t say how many apps have been developed for Passbook, but 22 are featured in the curated “Apps for Passbook” section of the App Store.

“We were amazed at the high uptake,” Phil Easter, American Airlines’ director of mobile apps said. “Apple has allowed an app developer like us is to put features right in front of the user where before, that space was off limits.”