dangrossman

With the Calais Auto Tagger plugin, you’ll never have to think of tags for your posts again. The plugin uses the Open Calais API to perform semantic analysis of your post text and suggest tags for you. Add them to your post with just a click.

WP Calais Auto Tagger

The plugin performs semantic analysis of your posts to suggest tags using Open Calais.

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.

WP Calais Auto Tagger vs YQL Auto Tagger