You've found your book. Let's say it was Cyberspace Romance. Notice that you've also found something else. Look at the titles of the books surrounding your title: Online Matchmaking, Beyond Friendship and Eros, Programs to Reduce Teen Dating Violence & Sexual Assault.
Because call numbers arrange books by subject, books near each other will be about similar topics. Once you find a book on your topic, you may find something even better by browsing the shelves around it.