The document discusses several taxonomy modules for Drupal:
- Primary Term allows assigning a primary term to nodes for better information architecture and URLs.
- Taxonomy Manager helps manage and control taxonomy terms to prevent uncontrolled growth of tags.
- Content Taxonomy and Taxonomy Image provide additional controls and functionality for taxonomy terms.
- Geo Taxonomy links taxonomy terms to geographic locations for tagging nodes with locations.
- OpenCalais allows automatic tagging of content by extracting terms from Thomson Reuters.
- In Drupal 7, taxonomy terms are fields, which changes how terms can be associated with content and reduces need for some modules.