To go specific on my suggestion:
Could there be an option when creating m4b-"audiobooks" to have the possibility to enter an amount of minutes, after which another chapter will be added into the stream? That way, at least I can skip forward and backward...

Also, I'd love to see an option in batch encoding, where I could "merge" the selected files into one big encoded file - this is especially helpful, when I download free audiobooks, that are offered as podcasts (mostly mp3) and convert them to m4b (saves space on the Ipod & because of the "marker"-option, to go back where I left of the last time). One caveat though: this would include some sort of "arranging the order of the original files" in the batch encoder's window.

Thanks for listening and considering.