WordPress 2.3 has a built in native tag management. However it's limited and you need some plugins to exploit it.

• A basic input tag during edition
• Basic Tag Clouds
• Tags of the current post

Simple Tags is THE perfect tool to manage perfeclty your WP 2.3 tags It was written with this philosophy : best performances, more secured and brings a lot of NEW functions.

• Administration
• NEW Related tags !
• NEW AJAX Admin features !
• NEW Tags suggestion from Yahoo Term Extractions API, Tag The Net and Local Tags with AJAX request

+ Compatible with TinyMCE, FCKeditor, WYMeditor and QuickTags

• NEW Improve performance !
• Auto tags !
• Auto link tags in post content
• Importer for embedded tags
• type-ahead input tags / Autocompletion
• Click tags
• tags management (rename, delete, merge, search and add tags, edit tags ID)
• Edit mass tags (more than 50 posts once)
• Possibility to tag pages (not only posts) and include them inside the tags results
• Embedded tags (tagstag1, tag2[/tags]) for compatibility with old plugins
• Easy configuration ! (in WP admin)
• Blog
• Meta keywords generate from tags in your header's blog
• Technorati, Flickr and Delicious tags
• Dynamic Tag Clouds with colors with Widgets (random order, etc)
• Related content since common tags
• Possibility to add related posts inside RSS
• Extended the_tags function (outside the loop, technorati, etc)