Bartosz Romanowski

This plugin provides a simple [tag] shortcode.
Replacing patterns:
[tag]tag name[/tag]
<a href=”http://yourdomain.com/tag/tag-name/” title=”tag name”>tag name</a>
[tag slug=”tag-name”]your text[/tag]
<a href=”http://yourdomain.com/tag/tag-name/” title=”tag name”>your text</a>
[tag name=”tag name”]your text[/tag]
<a href=”http://yourdomain.com/tag/tag-name/” title=”tag name”>your text</a>

Simple Tag Shortcode

This plugin provides a simple [tag] shortcode.

jaric

Basing on WordPress Plugin “tagthepress” .It using for tag suggestions by Yahoo cas API 
http://tw.developer.yahoo.com/cas/
With this plugin, you will be able to use the the Web service for your posts. Just click on <code>Fetch tags</code> and the title, content and optional excerpt of your post will be analyzed by Yahoo cas API in order to find words that could be useful as tags.
It currently works with English, Chinese

AutoTags

Basing on Wordpress Plugin "tagthepress" .It using for tag suggestions by Yahoo cas API

Simple Tag Shortcode vs AutoTags