I just heard about this brand new website!
Its a website that helps you find books by comparing the content of the books themselves, similar to the way Pandora.com matches music for music lovers. They are attempting to help you find books with similar themes and writing styles to books you've enjoyed in the past. Comparing elements like description, pacing, density, perspective and dialog while also allowing specific details like "medieval weapons". There are over 6 million book titles in the database and counting!!
I figure this could be a great tool for buyikng books as gifts. If you know someone loved a certain book, you can get a great comparable book and also learn about a whole new slew of authors that you would never have looked for at the bookstore. I am loving this!!!!