The sharp minds at Feisty Goat Interactive have recently updated their iOS app BeerQuest. No matter where you are, BeerQuest helps you find and share places nearby for a delicious brew. Feisty Goat built the mobile REST API behind the app as well as the web site using CodeIgniter. From one of their developers:
I looked at other PHP frameworks along with other languages (Ruby, Scala) but kept going back to CodeIgniter. Its flexibility and ease of use are second to none in my book.
Of course we think that Feisty Goat Interactive made a great choice with CodeIgniter, but judging by the push notification in the first screenshot, they appear to have good taste all around.