"PingMag is a web magazine about art, design, technology, and more. It is based entirely on our own personal likes and interests, and we hope it will be built up, and expanded on, by thoughts and comments posted by you, our readers." The site offers some great content, such as this interview with the founder of Die Gestalten Verlag books in Germany (one of the publishers that we stock here at UPPERCASE.)
This website offers a place to view and discuss book cover design, as well as interviews with leading cover designers such as Jon Gray whose work is shown above. While you're there, check out the site authors works which will lead you to some free downloadable paper toys that you can printout and assemble.