I recently upgrade a blog of mine from Wordpress 2.2 to Wordpress 2.3. My wife and I don't post on the blog much (looking for better ideas on how to utilize the site), but it's great to keep around to test the latest and greatest Wordpress has to offer. In my view, the most important new feature in Wordpress 2.3 is the baseline introduction of tags (also called taxonomy or even categories in other CMS applications).
ultimate tag warrior
Donncha: Ultimate Tag Warrior for Wordpress
"The Ultimate Tag Warrior plugin for WordPress is a great plugin. It does the job of handling tags rather well. I’ve noticed many hits from Google searches that go to a tag page instead of a category page of the same name so there’s something there that Google likes. I love it! Christine Davis did a super job filling a niche with the “ultimate” tool that anyone could want."

