The Login Warning Banner plugin for WordPress allows an administrator to create a custom, pre-authentication, warning header and message. The plugin
Allow OpenID based commenters to add their thoughts via comments on your WordPress blog. This plugin is not an OpenID server.
A login alternative to OpenID, designed for blogs and anything else you can think of!
Instantly requires that users be logged in to visit your site. Also serves as a good base for expansion. No interface, just activate and go! Requires
Authenticates users through Active Directory.
With this plugin you can manage of WordPress users via Google Apps.
Feed Key adds a 32bit (or 40bit) key for each of your users, creating a unique feed url for every registered on user the site. This allows you to rest
Have your blog run off the user table of another blog, in the same database.
Permit access to your blog only to the logged in users
The Rails Integration_API plugin enables single sign-on between a
Rails application and any number of Wordpress installations.