Rich I think that's brilliant, *very* fast and stylish my only comments would be:
Rather than the quicklinks at te bottom, why not have them at the side too when it's not displaying subcategories?
When you copmare different books at once it's not immediately clear what to do next if you want to add more books rather than buy them straight away - again perhaps if you had the main categories down the side rather than just at the bottom it'd be clearer?
at first glance i thought the two search boxes were a login/password combo - probably would have understood what to do from compare page better if i hadn't.
a sitemap of all categories and subcategories is always nice from an
seo pov, linked to from every page.
other than that well done - jealous
