I've just discovered the app Overdrive, this can be downloaded onto ipad, iphone and other devices to enable you to borrow books and Audio books for free from your local library.
They can be loaned for 7, 14, and 21 days.
Maybe you already know of this but I have only just found it and am really enjoying listening to audio books on it.
All you need is your local Library no and pin no to enable you to use it. go take a look I think its great.