Audio books have always been extremely popular, but the rise in popularity of MP3 players and iOS devices has seen this increase exponentially. There are a number of online services that can be used to buy audio books for your device, but one of the most successful is Audible.

The app is only available in the US, but it provides access to your entire Audible library wherever you may be, providing you have access to a wifi connection. As audio books tend to be fairly lengthy, and therefore often quite large, downloads can be paused and resumed as required and there are a number of options when it comes to navigating long books.

A familiar progress bar can be used to skip through a book, while a dedicated button is available to skip back 30 seconds. Chapters allow for wide scale navigation, and the ability to create bookmarks means that you can easily jump to a particular section of a book.

The speed of narration can be adjusted - strange, but interesting if you're in a hurry - and social networking features make it possible to share your listening habits with friends. With a sleep mode available, Audible can be used to drift off to sleep as well.