Quoted: Calais is a rapidly growing toolkit of capabilities that allow you to readily incorporate state-of-the-art semantic functionality within your blog, content management system, website or application.

Tag cloud for annotated bookmarks of Jacob Kaplan-Moss (of Django fame).

I've just implemented user-specific pages, and tags on G02.ME....getting close to complete.

Tag pages show the most recently popular URL's that have had a particular tag added to them.

All the popularity pages (including the home page) are using a patent pending algorithm I developed to efficiently decay scoring events over time (current half-life for all scoring events is 1 day).

Django template tags and filters documented here.

Cool tag cloud module for Drupal

Taxonomy extensions - CCK Freetagger looks interesting for free tagging of content types.

Quoted: The Taxonomy module organizes taxonomies into vocabularies which consist of one or more terms. Vocabularies group terms that describe an aspect of the node.

Ignite Seattle is using this - looks pretty cool.

Quoted: Jiglu: Tags that think - intelligent, automatic tagging for your blog