Drupal 6 SEO | Must have modules

These are the modules, I think must be installed for SEO.

PathAuto
A must-have module for all Drupal installations. Helps creating SEO friendly URL for any node type, Taxonomy, User pages.

XML Sitemap
XML sitemap automatically creates a sitemap that conforms to the sitemaps.org specification. This helps search engines keep their search results up to date.

Page Title
Allows to set dynamic page titles for different nodes.

Nodewords (AKA Meta Tags)
Allows you to specify meta keywords and descriptions for each page (or node) as well as the homepage. It also supports GeoURLs .

Global Redirect
Provides features like remove the trailing slash from requests. so that dreaded duplicate content is avoided that search engines seem to hate. It creates 301 redirects for two potentially duplicative URLs. checks for case sensitive urls as well.