catWalker plugin by kwiliarty helps you take better advantage of WordPress categories to organize your site and offer transparent navigation. At the same it introduces a custom taxonomy of its own: “Attributes.” Why a custom taxonomy? Most importantly because the native categories apply only to posts, and never to pages. There are a few plugins that manage partial integration of categories and pages, but it’s an uphill battle. By starting from scratch we get to designate that attributes can apply both to pages and posts.
Download and info: http://wordpress.org/extend/plugins/catwalker/