Konstantin Sokolov

Performs automatic keyword extraction. Adds a keyword taxonomy for browsing and a keyword extraction metabox in the post editing page. 
Available in English and Mandarin.

Eventflow Keyword Extraction

Automatic keyword extraction for SEO enhancement and improved user experience.

jim912

Outputs meta description and meta keywords in the element head. 
Notice! Current version japanese only, yet.
<h3>Links</h3>
“<a href="https://wordpress.org/extend/plugins/ps-auto-sitemap/" title="WordPress sitemap plugin">PS Auto Sitemap</a>” is a plugin automatically generates a site map page from your WordPress site. 
It is easy to install for beginners and easy to customize for experts. 
It can change the settings of the display of the lists from administration page, several neat CSS skins for the site map tree are prepared.
“<a href="https://wordpress.org/extend/plugins/ps-disable-auto-formatting/" title="WordPress formatting plugin">PS Disable Auto Formatting</a>” 
Stops the automatic forming and the HTML tag removal in the html mode of WordPress, and generates a natural paragraph and changing line.
“<a href="http://www.web-strategy.jp/" title="CMS service with WordPress" rel="nofollow ugc">CMS service with WordPress</a>” provides you service that uses WordPress as a CMS.

Meta Manager

Outputs meta description and meta keywords in the element head.

Eventflow Keyword Extraction vs Meta Manager