Bloafer

Use this plugin to apply <a href="https://wordpress.org/extend/plugins/share-rail/screenshots/" rel="ugc">floating shares</a> to your posts and pages.
This is very similar to the one found on mashable.com.

Share Rail

Use this plugin to apply floating shares to your posts and pages.

arstropica

Developed at <a href='http://nci.com' rel="nofollow ugc">NCI</a>. 
The Social Media Icons Widget is a basic sidebar widget that displays icon links for the user’s social media profile URLs. 
The widget includes 28 different freeware icon sets with different combinations of icons.  The default icon set features all the icon types found in the other icon sets.
Icons may be ordered using drag/drop in the widget panel
It is also possible to create custom icon sets by adding a folder with the icons you want to appear in your sidebar.
<h4>Included Icons</h4>
Note: Not every icon set designer creates the full range of icons.
<ul>
<li>Facebook</li>
<li>Google+</li>
<li>Twitter</li>
<li>LinkedIn</li>
<li>Flickr</li>
<li>YouTube</li>
<li>Digg</li>
<li>Reddit</li>
<li>StumbleUpon</li>
<li>Buzz</li>
<li>Vimeo</li>
<li>WordPress</li>
<li>Yelp</li>
<li>RSS</li>
<li>Contact</li>
<li>Delicious</li>
<li>Website</li>
<li>GitHub</li>
<li>Goodreads</li>
</ul>
All included icons are 32px x 32px. 
Custom icons of any size may be used.
<h4>Included Icon Sets</h4>
<ul>
<li>3D Statuette</li>
<li>3D Vector</li>
<li>Breakthrough</li>
<li>Circular</li>
<li>Creatures</li>
<li>Default</li>
<li>Furry Cushion</li>
<li>Grass Textured</li>
<li>Ice Cubes</li>
<li>Latte Art</li>
<li>Moleskin</li>
<li>Old Paper</li>
<li>Painting</li>
<li>Paper</li>
<li>PC Monitor</li>
<li>Picasso</li>
<li>Puzzle Piece</li>
<li>Scientific</li>
<li>Simple Vector</li>
<li>Sleek Blue</li>
<li>Sleek Green</li>
<li>Sleek Orange</li>
<li>Sleek Purple</li>
<li>Sleek Red</li>
<li>Sleek Yellow</li>
<li>Social Snow</li>
<li>Vintage Postage Stamps</li>
<li>
Yammy
</li>
<li>
Create your own icon sets by adding a folder to the “images/iconset” directory.
</li>
<li>Choose whether links open in a new window.</li>
</ul>
<h3>Arbitrary section</h3>
The icons in this plugin are distributed freely by a 3rd party and either licensed to be used in a personal or commercial capacity under several licenses including the Creative Commons, FastIcon and various other licenses.

Share Rail vs Social Media Icons Widget