Miled

WordPress Social Login allow your website readers and customers to register on using their existing social accounts IDs, eliminating the need to fill out registration forms and remember usernames and passwords.
WordPress Social Login also allow you to import users contact list from Google Gmail, Facebook, Windows Live and LinkedIn.
WordPress Social Login gives you absolute control over users access to your website and comes a list of rules and restrictions for you to setup.
Easy to customize and integrate 
Wordpress Social Login come with a simple but flexible and fully customizable authentication widget. And if you are a developer or designer then you can customize it to your heart’s content.
Wide variety of providers 
Depending on the audience you’re targeting, you can choose from a wide variety of providers and services including: Social networks, Microblogging platforms, Professional networks, Media, Photo sharing, Programmers and Gamers networks.
Currently supported providers 
Facebook, Google, Twitter, Windows Live, Yahoo!, LinkedIn, Reddit, Disqus, Tumblr, Stackoverflow, GitHub, Dribbble, Instagram, 500px, Foursquare, Steam, Twitch.tv, Mixi, Vkontakte, Mail.ru, Yandex, Odnoklassniki, Goodreads, Skyrock, Last.fm, AOL and PixelPin.
Free, unlimited and white-label 
Wordpress Social Login is open-source and completely free. The source code is publicly available on <a href="https://github.com/hybridauth/WordPress-Social-Login" rel="nofollow ugc">GitHub</a> for anyone to help and contribute. You are free to use a WordPress Social Login in commercial projects as long as the copyright header is left intact.
Big thanks to everyone who have contributed to WordPress Social Login by submitting Patches, Ideas, Reviews and by Helping in the support forum.

WordPress Social Login

WordPress Social Login allow your visitors to comment and login with social networks such as Twitter, Facebook, Google, Yahoo and more.

Artberri

When someone comments on your blog and writes a comment with his/her URL, is leaving more information than you think. This plugin displays web pages and profiles of those users in the dashboard, so you can add them as friends if you are in the same social network.
This is possible thanks to the Google Social Graph API. The profiles are showed because the commenter claims them as its owner on his web linking them with <code>rel="me"</code>. The ones which are with italic font are not reliable and they could not be of the user.
Comments, questions and bug reports are welcome: <a href="http://www.berriart.com/meet-your-commenters/" title="Meet Your Commenters" rel="nofollow ugc">http://www.berriart.com/meet-your-commenters/</a>

Meet Your Commenters

Displays web pages and social networks' profiles of your commenters in the dashboard.

WordPress Social Login vs Meet Your Commenters