alexisabarca

With this very simple plugin you can use the blog URL to authenticate with OpenID using an another OpenID provider. 
called Delegation.
In order to maximize performance the vars are contained in plugin file rather than storing in a database.
Due to security issue (https://wordpress.org/news/2011/06/passwords-reset/) php file is gpg signed, ID 7ED1BC0C.

Open ID Delegate

This plugin adds the necessary tags to be able to use your blog URL as OpenID address using another OpenID provider

gdeglin

Extremely easy to use. Just install and enter your email address. Users will immediately be able to log in with just a few clicks using Facebook Connect through Lil’Omi.
Users who login with Lil’Omi can customize a cool 2D avatar for themselves and select a username which becomes their default WordPress username and avatar on your site with a simple authentication step using Facebook Connect.
Lil’Omi makes user sign up simple. If a user has already signed in with Lil’Omi on one WordPress site, they are automatically signed into any other WordPress or Buddypress site that also uses the plugin.
Changes that this plugin makes to your site:
<ul>
<li>Lets your users have a unique, customizable avatar with millions of possible combinations.</li>
<li>Adds a “Login with Lil’Omi” button to your log in, registration, and comment forms visible to logged-out users.</li>
<li>Allows users to sign in via Facebook without sharing their personal name or photo with your site.</li>
<li>Makes new user registration much easier for users.</li>
<li>Increases the amount of users that sign up for your site by automatically signing in users that have already used Lil’Omi on other sites.</li>
</ul>

Lil'Omi Avatars

Lil'Omi adds cross-site Facebook Connect support to your WordPress or BuddyPress site.

Open ID Delegate vs Lil'Omi Avatars