In my second installment of Displays For the Reluctant Librarian I'd like to nominate "By The Book" a weekly installment that appears in the The New York Sunday Times Book Review. Each week a different author or celebrity (usually someone who has a new book out or has been in the news of late) answers a series of questions that revolve around reading that always include a number of authors and titles they're either reading or recommending.
Almost all libraries subscribe to the New York Times. And if your's happens to not, you can always download and print the weekly column from the website. You can search the database of past featured guests or print the most current installment. After that it's just a matter of searching your catalog for titles written by the featured guest and titles said guest either mentions by title or author. Like thus:
It doesn't require you create signage, it promotes titles that may not have circulated recently and it can be constantly refreshed as you either run out of books to display or choose to change every week (we change ours weekly with every new edition of the Book Review).
Most weeks I can not only find a minimum of three books mentioned in the article that we own in our library collection to display but I also see at least one of those books circulate as a result.