Since I have several types of books I break them down into:
Sewing, crochet/knitting, embroidery, etc. Then I break down my quilting books by applique, piecing, holidays, baby/children, etc. I have a five shelf case for just these. Since I am a prolific reader I also have my reading books stashed elsewhere. I could probably start my own library if I wanted too. I have given a lot of books away, but for some reason they do not do too well in a garage sale. Still haven't figured that one out.
I forgot to mention that I also have several 3" binders broken down by categories with stuff off internet, from magazines, etc.