Ruven

This plugin provides a function to output links to share a post to Facebook, Twitter, and Google+.
Selected themes by Ruven will display the links automatically when the plugin is activated. 
In other themes you will have to edit the templates in your theme in order to output the links.
Here an example of outputting the links in as list:
<pre><code><?php
if(function_exists('ruven_sharing_links')) {
 echo '<ul class="sharing-list">';
 $sharing_links = ruven_sharing_links();
 foreach($sharing_links as $sharing_link) {
 echo "<li>$sharing_link</li>";
 }
 echo '</ul>';
}
?>
</code></pre>
<h4>Usage</h4>
<pre><code>$sharing_links = ruven_sharing_links( $get_array, $include, $open_in_new_tab, $class );
</code></pre>
<h4>Parameters</h4>
$get_array 
(bool) (optional) If you want the return value to be an associative array (title, URL) or an array of HTML links. By getting an associative array, you are able to customize the output more.
Default: false
$include 
(array) (optional) If you don’t want all platforms (Facebook, Twitter, and Google+) included, you can specify here which you want specifically to be returned. E.g. <code>array('Twitter', 'Facebook')</code> would only return Twitter and Facebook links.
Default: array()
$open_in_new_tab 
(bool) (optional) If you want the sharing dialog to be opened in a new tab/window or not.
Default: true
$class 
(array) (optional) Classes you want to add to the links. E.g. <code>array('sharing-button', 'big-button')</code>
Default: array()
<h4>Return Value</h4>
If the value of <code>$get_array</code> is <code>false</code> (default), the function returns an array of HTML links.
If the value of <code>$get_array</code> is <code>true</code>, the function returns an associative array of the title (e.g. “Twitter”) and the URL to share the post.

Ruven Themes: Sharing Links

RT Sharing Links provides a function to output links to share a post to Facebook, Twitter, and Google+.

demixpress

This plugin makes it even easier and better to display <a href="http://addthis.com" rel="nofollow ugc">AddThis</a> tools for your WordPress site, including share buttons, follow buttons and recommended contents.
To make this plugin to work:
<ol>
<li>You must have an AddThis account.</li>
<li>You CAN NOT use other AddThis plugins.</li>
</ol>
About Social Sharing Optimization
This plugin doesn’t do anything to optimize the social sharing results, if you need this, try a related plugin, such as:
<ul>
<li><a href="https://wordpress.org/plugins/wpsso/" rel="ugc">WordPress Social Sharing Optimization</a></li>
<li><a href="https://wordpress.org/plugins/wonderm00ns-simple-facebook-open-graph-tags/" rel="ugc">Facebook Open Graph, Google+ and Twitter Card Tags</a></li>
</ul>

(dp) AddThis

Makes it even easier and better to display AddThis tools (share buttons, follow buttons and recommended contents) on your WordPress site.

Ruven Themes: Sharing Links vs (dp) AddThis