WordPress 2.3 has included tag support, but it comes without any tag management function or interface. Thus, WordPress users community has created and developed plenty of tag management plugins with different designs, user interfaces, and vary degree of simple features to advanced functions. Here’s another tag management plug-in for WordPress version 2.3 or above.
Tag Managing Thing allows users to edit your tags. Once activated, users can find a “Tags” menu item uder the “Manage” section of wp-admin, there is a Tags menu item that will open the Tag Managing Thing interface. Users can change the name and slug of the term, delete a term, split a term into multiple terms and merge other terms into the selected term.
Tag Managing Thing allows selecting the taxonomy to work with. Currently in WordPress there is a category and a post_tag taxonomy. Selecting a taxonomy allows editing the terms within that taxonomy.
Download Tag Managing Thing.
Update: The plugin is no longer been updated, and in addition, tag management is now built into WordPress core.