I went through this a couple of years ago. I also use Overdrive and love it. (mostly I get audio but some kindle) I had so many bookcases overflowing with books that it was getting ridiculous. I got rid of most of them, keeping my absolute favorites. As I went through them I was amazed at how many I didn't want and to this day I don't miss them.
I'm a huge lover of audiobooks and have several ipods to accomodate them. I still can't seem to part with my nursing books, even though they are really old. But other than them the books I kept are extra special. I'm so into getting rid of stuff these days
