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.

Mervin Praison

This plugin helps you add Google authorship markup to your WordPress site, allowing your Google Plus profile picture to appear in Google Search results.
Features: 
* Easy 4-step setup process 
* Multiple author support 
* Multisite compatible 
* Shortcode support

WP Google Authorship

Nice

Google Plus Profile Picture appear in Google Search. Very Easy to implement. Including Google authorship for multiple authors and multisite.

Sharing is Caring vs WP Google Authorship