MyOpenID plugin allows you to use your blog as your OpenID identity by delegating it to an external provider such as Symantec PIP or claimID.
This plugin delegates OpenID to MyOpenID.
Google Identity Toolkit (GITkit) helps relying party (RP) websites to support federated login easily (http://code.google.com/apis/identitytoolkit).
Login by Auth0 provides improved username/password login, Passwordless login, Social login and Single Sign On for all your sites.
Gets the data from your NoseRub account and lets you use it on your weblog. Supernifty.
This plugin adds the necessary tags to be able to use your blog URL as OpenID address using another OpenID provider
Use OpenID Connect to log in to other webservices using your own WordPress.
This plug-in adds a `Login with MySpaceID' button to the login page.
This plugins had the needed code to the header of your blog, to detect your OpenID account at http://openid.sapo.pt, look at my blog source code and check the header (http://antoniocampos.no-ip.com).
Social Login by Janrain
VidoopConnect makes it easier than ever to sign up and login to your site by
letting your visitors reuse their existing accounts from sites like Google,
Yahoo, AOL, Facebook and MySpace, or any other OpenID provider.
Facebook Connect & Facebook <> WordPress sync using Facebook Graph API ... more soon
Connect Wordpress to the Scouting Nederland OpenID-server
Allow user login or registration using Seqrly service. Additionally, OpenIDs for authentication of users and comments is also supported.
REST API Authentication
Secures the unauthorized access to your WordPress sites/pages using our WordPress REST API Authentication plugin.