slaptijack

Suggest Tags creates a list of tag suggestions based on the content of the post you are editing. Since the Yahoo! Term Extraction API is going to be shutdown at the end of August 2009, this plugin uses the term extraction API from tagthe.net.

Suggest Tags

Suggest Tags uses the tagthe.net tagging web service to generate a list of tag suggestions.

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

Suggest Tags vs AutoTags