I ran across a story at Mainstreet.com, a personal finance portal, The Most Stolen Library Books, by Jeanine Skowronski, whose informal survey of librarians is pretty accurate. My only quibble is that the books in question are not so often stolen outright as they are legitimately checked out and then not returned. In our system they are more often marked "assumed lost", rather than "missing".
Someone has gone to the trouble to get a library card to check out the one book that they need or want, and when they don't return it, they forfeit their library privileges. I've always felt that this is a class issue. People who are living hand-to-mouth, with little disposable income, and more chaos in their lives than the well-off would believe, will accept their loss of library privileges before they will pay for a lost book. I often sense that this is the real story behind the "I have a card, but I left it at home" excuse that we get from people asking for a computer guest pass.
This is borne out by Skowronski's selection of test prep books as one of the most stolen classes of books. In fact, the test prep books that go missing are the ones for low-level entrance or certification, for the GED, the ASVAB, and the TABE. Higher level test prep books, for the GRE or the LSAT, do not get lost nearly so often.
The article mentions Zane, an author of explicit black erotica. These titles disappeared so quickly that we simply gave up buying them. And Dave Peltzer's A Child Called It: yes, I am always looking for donated copies for replacements.
We had students from a local university, FAMU, repeatedly asking for David H. Jackson, Jr.'s A Chief Lieutenant of the Tuskegee Machine: Charles Banks of Mississippi . We don't take requests for university course materials, but inevitably one got through to interlibrary loan, and was then lost, which cost us dearly. Our solution was to purchase a copy, held at the reference desk, for use in-library only.
Another title we had to purchase for in-library use only, after many lost copies, to forestall interlibrary loan requests, is Behold a Pale Horse, by William Cooper, a conspiracy book about the "New World Order".