Easy Verification 1.1
This plugin will allow you to easily verify your site for Google and Yahoo!. By Allan Collins.
Enhanced WP-ContactForm 2.2.2
WP Contact Form is a drop in form for users to contact you. In the message it sends to you it gives the page the user visited before the contact page, as well as the original outside referer. It can be implemented on a page or a post. By Joost de Valk.
Google XML Sitemaps 3.1.3
This plugin will generate a sitemaps.org compatible sitemap of your WordPress blog which is supported by Ask.com, Google, MSN Search and YAHOO. Configuration Page By Arne Brachhold.
HeadSpace2 3.6.27 Meta-data manager on steroids, allowing complete control over all SEO needs such as keywords/tags, titles, description, stylesheets, and many many other goodies. By John Godley.
Registered Users Only 1.0.3
Redirects all non-logged in users to your login form. Make sure to disable registration if you want your blog truely private. By Viper007Bond.
Reveal IDs for WP Admin 1.1.2
WordPress 2.5+ only. Reveals hidden IDs in Admin interface that have been removed with WordPress 2.5 (formerly known as Entry IDs in Manage Posts/Pages View for WP 2.5). See Options Page for options and information. By Oliver Schlöbe.
Robots Meta 3.0.11
This plugin allows you to add all the appropriate robots meta tags to your pages and feeds, disable unused archives and nofollow unnecessary links. By Joost de Valk.
SEO Slugs 1.0
Removes common words like ‘a’, ‘the’, ‘in’ from post slugs to improve SEO. By Andrei Mikrukov.