"These are actually the bookcases combining my books and my husband's. The left end is (more or less) his non-fiction area, the rest of the non-fiction is pretty much mine. On the right end, almost 100% of the science fiction is his, and the rest of the fiction is mine. I read science fiction, too, but he reads it almost exclusively. Other shelves in the den hold decades worth of paperbacks."Addendum: updated from 2013...
"We moved house a little over three years ago, and while we still have the white bookcases shown in the photo you reposted recently, they are configured differently and in different areas.
The attached photo is of half the bookcases in our "studio", and the ones on the left represent all the science fiction paperbacks my husband has purchased and read since he switched from comic books at age 14. They are double-depth, and roughly in alpha order by author. This year he decided to re-read his way through Heinlein and we had all but two titles on hand. Thank goodness he switched a few years ago to borrowing from the library.
I started using an app and website called Libib. I've catalogued our entire library with it, so when I'm at a bookstore I can quickly check to make sure an attractive title was not equally attractive in the past and already on our bookshelf."