In our Drupal sites for our library and now in our Knowledge Hub we've been using LCC to catalog items and then using HILCC to produce a navigatable architecture in our Drupal sites.
This functionality is now available to the public at large as a Drupal module, which you can download here:
HILCC is a hierarchic classification scheme developed originally at Columbia University Libraries, designed to offer library catalogs a way to easily cluster similar-subject items for navigation. HILCC is licensed under a Creative Commons BY-NC license.
For now it's only available for Drupal 5, but a D6 version is in the works.