I really like it when I open a book and find an ephemeron or other associated object. A couple months ago I bought a used copy of Dr Jekyll and Mr Hyde from a local used bookstore. I opened it tonight to find a receipt dated January 1992 from the University of Virginia bookstore. I've found bookmarks from other bookstores in new books: bookstores return books to publishers and distributors, who then send the books back out to other stores; ephemera caught up in the process get a free ride. I've also found author signatures in books not marked as signed: sometimes returns are responsible, and sometimes authors find copies of their books in stores and sign them. All these ephemera give the book a sense of history, and help wash away anonymity. I guess BookCrossing does something similar for books one gives away, and Where's George does something similar for US currency. But there's nothing like real books and their associated real ephemera.