Computerized Readers' Tools
Many tools exist that use computers to generate suggestions for readers.
Reading Log Tools
Although these sites are primarily designed to track all the books you read, they each have excellent tools for recommending works you might enjoy based upon your reading history.
Goodreads is designed as a social media site to share the books you have read with your friends. Goodreads will make recommendations based upon an individual title, all the books you have read that share a common tag you have created, or a predefined genre type given your reading patterns. Goodreads also allows friends to recommend books to each other.
LibraryThing is designed to catalog books you own or to create virtual collection out of the books you have read. For any book on your bookshelf, you can see books LibraryThing itself recommends as well as recommendations made by LibraryThing users. The site also includes a social media aspect where groups discuss books they enjoy.
Shelfari uses wiki tools to combine the social media aspects of Goodreads with the cataloging aspects of LibraryThing. Shelfari allows other members of the community to make recommendations to friends. Because it is owned by Amazon.com, you can also explore the Amazon catalog to find books you might enjoy.
These tools all work take a book you enjoy and finding connections to other books with similar features.
Literature Map takes the name of an author and generates a visual array of authors that write similar works. The closer an author's name is to the name you entered, the more similar their works should be.
NoveList Plus is a subscription database which Naperville Public Library pays for its cardholders to be able to use. NoveList provides reader's advisory information for fiction and nonfiction titles with lists of read-alikes, book reviews, feature articles, book discussion guides, and booktalks.
YourNextRead centers a book title, author, or genre in a small tree with each branch giving a direction to explore. You can rate each branch up or down to help the algorithim give better results for both you and future users. GoodReads users can enter their entire library to improve the tool's results.
whichbook has twelve scales that describe different aspects of a fiction book. You can move up to four of the sliders to create millions of combinations. You can also specify characteristics of the characters, plot, and setting. whichbook then provides a list of books which match the factors you've selected.