PSMAN

TagGator is an auto tagging plugin, Just write enter a few keywords representing your contents, TagGator will automatically scan your posts for these keywords, and tag them according to the results.
A Pro Version of TagGator is now available with the following features:
<ul>
<li>Auto Tagging: Your posts are tagged automatically when you create posts.</li>
<li>Autoblog friendly:Taggator works with most autoblogging solutions, tags are created automatically when the posts are generated.</li>
<li>Keywords To tags: Just write different keywords that represent you tags, Taggator will create the tags, and assign them.</li>
<li>Set & Forget: You only need to configure TagGator once. once done, you won’t have to worry about tags anymore</li>
</ul>
<a href="http://codecanyon.net/item/taggator-pro-wordpress-auto-tagging-plugin/1725033?ref=AngryByte" rel="nofollow ugc">Click here to learn more & get TagGator Pro</a>

TagGator

TagGator Automatically tag to your posts so you dont have to! Tag your posts based on their contents automatically.

Selim Şimşek

Options:
<ul>
<li>Determine the number of tags to be shown per page</li>
<li>Create a custom style for the link to be shown</li>
<li>Select the area you want to add link (pages, posts)</li>
</ul>

Tag Linker

This plugin adding links to post or page content that match tags in use.

TagGator vs Tag Linker