Mark (podz)

With the SocialMyBlog widget you can easily add social buttons to the sidebar of your blog, and all with one simple widget for all the main social sites, this widget supports many different social sites allowing users to share your blog with thousands of people.

SocialMyBlog

A simple and easily adjustable social plugin for your blog to help you reach more visitors, includes facebook, google+, twitter, pinterest and more.

mczolton

The Zolton.org Social Plugin (ZOSP) is a simple plugin for WordPress that 
integrates a blog with popular social networking sites such as Facebook and 
Twitter. I wrote this plugin to learn WordPress plugin development, and as a 
means to decouple these social networking features from my desired WordPress 
theme.
Features
<ul>
<li>Includes the Facebook JavaScript SDK in your WordPress theme.</li>
<li>Generates Facebook Open Graph tags for posts and pages.</li>
<li>Includes the Facebook Like Button and Send Button on posts and pages.</li>
<li>Imports the featured image / post thumbnail (if available) from a post or 
page for use as the featured image on Facebook.</li>
<li>Generates a Facebook Comment section for posts and pages.</li>
<li>Includes the Twitter Tweet Button on posts and pages.</li>
<li>Includes the Google +1 Button on posts and pages.</li>
<li>Includes the Pinterest Pin It Button on posts and pages.</li>
<li>Optionally hides WordPress comments.</li>
<li>Configurable via WordPress setting page.</li>
</ul>
Requirements
<ul>
<li>A Facebook App ID.</li>
<li>A Twitter account.</li>
<li>WordPress theme supporting featured images / post thumbnails.</li>
</ul>
<h3>Known Issues</h3>
<ul>
<li>“Leave a Comment” link is still visible when WordPress comments are disabled.</li>
</ul>

Zolton.org Social Plugin

A simple plugin for WordPress that integrates a blog with popular social networking sites such as Facebook and Twitter.

SocialMyBlog vs Zolton.org Social Plugin