Fairfax County Public Library's My Perfect Read provides personalized book recommendations.
You will receive personal recommendations on other titles you might enjoy - it's like having your own personal librarian!
Another subscription database useful for book recommendations is Books & Authors. This online resource has descriptions of thousands of recommended adult fiction titles from multiple genres (teen and children's titles, too!). It is useful if you want to know the sequence of a book series or if you are looking for authors who write in a similar genre or style to a favorite author.
Books & Authors also has a new feature called WHO WHAT WHERE WHEN that lets you browse by Character, Subject, Location and Time Period; it then gives you a visual representation of your matching books.