I've read Robert Bringhurst's The Elements of Typographic Style (for my history of the book class), and I liked it a lot. Some don't, but I think it does a good job of it.

Has anyone read Jan Tschichold's Form of the Book? I checked it out once but didn't get a chance to read it.

On a more technical note, there's Donald Knuth's Digital Typography, which I'm reading at the moment and enjoying.

What else is out there?

You might like J. Abbott Miller's Dimensional Typography. An interesting small book with awesome graphics!

Do you know Keith A. Smith's Text in the Book Format and Structure of the Visual Book?

And a couple of books on the history of book design that I can recommend: American Book Design and William Morris and Five hundred years of book design.

Just now I'm reading (or rather dipping in and out of ) Andrew Haslam's Book Design it was the most practical book I could find on the shelf in a couple of big London bookstores last week.