I hollowed out an old book for my nook's case:
http://www.nookboards.com/forum/index.php?topic=1178.0
I wanted something that provided more protection when I was walking around, or had it in a bag, but didn't actually get in the way when holding it to read.
I'm trying to decide what to do with the nookcolor. It fits in the hollow book, but not as well, it doesn't close properly, but I also want something that integrates a stand of some kind. I've been using the NC for video and think it'd be nice to have it stand up on it's own.