jfoucher

This plugin uses the yahoo.com API to find the most relevant keywords from the content of your post, and then adds them as tags.
The tagging is fully automatic, so if you’re using a plugin like feedwordpress to display RSS feeds on your blog as posts, everything will get done as the feed posts are published. No user intervention necessary!

Auto-tags

Automatically add relevant tags to new posts.

New in version 1.2:
<ul>
<li>all changes only for WordPress MU (WPMU)</li>
<li>no changes for normal (single) WordPress</li>
<li>full WordPress MU (WPMU) support</li>
<li>runs on WPMU as an autoactivated plugin</li>
<li>the right place for installation is in wp-content/mu-plugins</li>
<li>activate/deactivate auto tag suggestion is only a site wide option</li>
<li>only site admin(s) can activate/deactivate auto tag suggestion</li>
</ul>
Features of version 1.1 are:
<ul>
<li>Show all your tags in alphabetically order as buttons on every post page</li>
<li>also tags with ‘ and ” in names are supported</li>
<li>To choose a tag, only a simple click on it is needed</li>
<li>All assigned tags are listed in alphabetically order. If you add or remove one or more tags, the tags will be automatically reordered for you</li>
<li>An administrator-option to switching off the auto-tag-complete (also called auto tag suggestion) on the whole WordPress-Blog</li>
<li>Full multi-language support. Translated languages are in the moment: English, German.</li>
</ul>
A complete description with some screenshots you can find on <a href="http://www.im-web-gefunden.de/wordpress-plugins/iwg-faster-tagging/" title="IWG Faster Tagging's Home" rel="nofollow ugc">Plugin Homepage at “im web gefunden”</a>.

IWG Faster Tagging

"IWG Faster Tagging" fixes some disadvantages from the original tagging-system at your editing post page..

Auto-tags vs IWG Faster Tagging