If you have a bunch of Audiobooks lying around and want to use them on your Ipdo/Iphone then it’s an advantage to convert them to .M4B files (then your device will remember where you left off the last time you listened, and not as .MP3 where you have to use the slider to get to where you were)..
I found this free util that will assist you, it’s not perfect – but it works most of the time and it’s free 🙂