To complement my coins and paper money collection, I also collect numismatic literature. Most of my library is about items I collect, but there are a few books that the subject interested me enough that I bought the book even though I never plan to collect anything that the book talks about.

One area that I've been concentrating more on is in collecting books signed by the author. While I'll buy a book with just the author's signature in it, I would rather have one with an inscription from the author to the original owner. I feel an inscription adds a little bit of atmosphere to the book.