Martin Lormes

Automagically adds Open Graph tags to your blog. Control how your posts and pages are presented on Facebook and other social media sites. No configuration needed.
When someone likes or shares your blog on Facebook, your header image is shown. If someone likes or shares a post, the featured image (post thumbnail) is shown. If you haven’t selected a featured image, then the plugin looks for the first image inside the post. If there aren’t any images in your post, then your blog’s header image is shown.
For more information on the Open Graph protocol go to http://ogp.me/

Open Graph Pro

Adds Open Graph tags to your blog. Control how your posts and pages are presented on Facebook and other social media sites. No configuration needed.

Piyush Mishra

The Open Graph protocol enables any web page to become a rich object in a social graph. For instance, this is used on Facebook to enable any web page to have the same functionality as a Facebook Page.
While many different technologies and schemas exist and could be combined together, there isn’t a single technology which provides enough information to richly represent any web page within the social graph. The Open Graph protocol builds on these existing technologies and gives developers one thing to implement. Developer simplicity is a key goal of the Open Graph protocol which has informed many of the technical design decisions.
<h4>For Developers</h4>
Use <code>add_action('open_graph_head_pre','your_function');</code> and <code>add_action('open_graph_head_post','your_function');</code> to edit the meta data. For an instance of the class.
Always use <code>open_graph_instance()</code> 
Read more on the Plugin URI > <a href="http://www.piyushmishra.com/plugins/open-graph.html" title="Plugin URI" rel="nofollow ugc">Open Graph WP implementation</a> or check out the FAQs

Open Graph WP implementation

Implements the Open Graph Protocol on a WordPress installation. Can be used by other plugins as a dependency.

Open Graph Pro vs Open Graph WP implementation