First, thanks for the great program! It definitely makes my ebooking easier and happier.
A couple of feature requests.
First, would it be possible to have an actual progress bar (indicating roughly how far along the progress is) for conversions, rather than just the rotating hourglass?
Second, I would find it handy to be able to "roll up" all of the books by a given author, to only have them all displayed if I clicked on that author. Sort of like the + feature on Windows folder view.