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.

chrisguitarguy

agencypmg

Google+ pages can verify their URLs by adding <code><link rel="publisher" href="your_plus_page_here" /></code> to the <code><head></code> section of a website.
This plugin lets you do that.
<a href="http://support.google.com/plus/bin/answer.py?hl=en&answer=1713826" rel="nofollow ugc">More information</a> on the Google+ help pages.

Rel Publisher

Rel Publisher is a simple plugin that lets you easily add <link rel="publisher" /> to your site.

Sharing is Caring vs Rel Publisher