You sign up, enter the name of a book, then find out what other folks who liked that book also liked; a tag cloud for the book leads to other books on this topic. Quite addictive, and I just used it to look at the info. around one book.
"writings cutting across and between politics, media, literature, history, law, science, medicine, philosophy, economics, music, film and more." Attractive and informative graphic design for ejournal homepage.