The default “category” and “tag” taxonomies in WordPress offer a lot of flexibility to those with imagination and in my development experience I have seen a wide range of creative implementations. With the introduction of custom taxonomies and their growing ease of use, though, we need no longer be bound to categories and tags. With the ability to create both hierarchical and non-hierarchical taxonomies and with the introduction of several new features in WordPress 3.1, now is the time, if you’re not already, to begin putting custom taxonomies to use.
