A while ago, when I first started getting into book forms, I stumbled upon the work of Sarah in Leeds (LittlePaperBird on Flickr and in blogland), and found it quite inspirational. The books were largely explorations of relatively simple folding and stitching patterns. Yet she tweaked them and built upon them in a way that made them seem so complex and elegant. She also does some nice, more traditionally bound books and boxes too.
I was recently browsing around the web and rediscovered some pictures of those folded book forms from a while ago. Great stuff.