michaelbeacom

Displays the social widgets from Facebook, Twitter, Google+ and Pinterest with your posts. It also adds some meta tags for opengraph and schema.org as recommended by Facebook and Google. The standard method to do this is by filtering the content of the posts, which is controlled by the options in the admin menu. Buttons can also be displayed by the shortcode [sic] with ability to disable individual buttons for that instance of the shortcode. You can also add it to your theme with do_action(‘sic_sharing’); where you want it to render.
Allows some custom text and css insertion as well as most options for the buttons in the admin page. Compatible with html5 (optional).

Sharing is Caring

Displays the social widgets from Facebook, Twitter, Google+ and Pinterest with your posts. Also adds some meta tags for opengraph and schema.org.

Paul Ryan

jojaba

the_elusive

Eduardo Larequi

Anil Natha

pkarjala

Authorizer restricts access to a WordPress site to specific users, typically students enrolled in a university course. It maintains a list of approved users that you can edit to determine who has access. It also replaces the default WordPress login/authorization system with one relying on an external server, such as Google, CAS, LDAP, or an OAuth2 provider. Finally, Authorizer lets you limit invalid login attempts to prevent bots from compromising your users’ accounts.
View or contribute to the plugin source on GitHub: <a href="https://github.com/uhm-coe/authorizer" rel="nofollow ugc">https://github.com/uhm-coe/authorizer</a>
Authorizer requires the following:
<ul>
<li>CAS server (2.x, 3.x, 4.x, 5.x, 6.x, or 7.x) or LDAP server (plugin needs the URL)</li>
<li>PHP extensions: php-ldap, php-curl, php-dom</li>
</ul>
Authorizer provides the following options:
<ul>
<li>Authentication: WordPress accounts; Google accounts; CAS accounts; LDAP accounts; OAuth2 accounts</li>
<li>Login Access: All authenticated users (all local and all external can log in); Only specific users (all local and approved external users can log in)</li>
<li>View Access: Everyone (open access); Only logged in users</li>
<li>Limit Login Attempts: Progressively increase the amount of time required between invalid login attempts.</li>
<li>Shortcode: Use the <code>[authorizer_login_form]</code> shortcode to embed a wp_login_form() outside of wp-login.php.</li>
</ul>

Authorizer

Integrates nicely with Google hosted domain/s. Couldn't be happier with how it works!

Integrates well with Google Logins

I've experimented this plugin on a multisite and everything works pretty well.

Works great even on a multisite setup

Authorizer limits login attempts, restricts access to specific users, and authenticates against external sources (OAuth2, Google, LDAP, or CAS).

Sharing is Caring vs Authorizer