The taxonomy_theme module allows you to change the theme of a given node based on the taxonomy term, vocabulary or nodetype of that node. You can also theme your forums and map themes to Drupal paths or path aliases directly.
This module provides an powerful interface for managing a taxonomy vocabulary. A vocabulary gets displayed in a dynamic tree view, where parent terms can be expanded to list their nested child terms or can be collapsed.
When activated, this module forces the 'all' parameter to taxonomy term URLs.
The taxonomy_breadcrumb module generates taxonomy based breadcrumbs on node pages and taxonomy/term pages.
Refine by taxonomy is another taxonomy browsing mechanism.