antonioandra.de

Enables your blog readers to suggest new post tags or upvote/downvote existing ones. 
Downvoted tags are eventually removed. 
A few more features are on the works as is the expansion of this readme document.
<h3>RoadMap</h3>
Add some frontend feedback; 
Add support for custom taxonomy tagging; 
Synonym dictionary; 
Better documentation, ui and automatic integration.

Author: António Andrade

Enables your blog readers to suggest new post tags or upvote/downvote existing ones.

freekrai

With the YQL Auto Tagger plugin, you’ll never have to think of tags for your posts again. The plugin uses the Yahoo Query Language to perform semantic analysis of your post text and suggest tags for you. Add them to your post with just a click.
This plugin requires PHP 5 and the cURL library (both of which are available on most web hosts).
Based on the Open Calais Auto Tagger by Dan Grossman – http://www.dangrossman.info

YQL Auto Tagger

The plugin performs an analysis of your post text and suggests tags for you.

Author: António Andrade vs YQL Auto Tagger