I love audiobooks! It allows me to listen the books I want in reasonable time. But not all books have a audiobook version. I just bought one of those and tried something to use the "text-to-speech" from the iPhone to read it to me and it worked!
Go to Settings - General - Accessibility - Speech and activate "Speak Screen". Now all you have to do is to swipe two fingers from the top. It works everywhere, but for me on iBooks or the Kindle App is the killer use case.
It even turns the pages and continues!