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.

alexpooley

Selectively add social network buttons such as digg, sphinn, etc to your posts or theme design.
I wrote this plugin because I wanted finer control over where and which buttons 
were placed on my site and in my posts.
Sometimes I have marketing posts so I want to link to Sphinn, but sometimes I have 
technical posts so Reddit would be a better choice. This plugin is flexible enough that 
if you want the same button in every post, then you can still modify your theme very easily 
to accomplish this.
You may place as many buttons, in as many places in your posts as you like.
This plugin handles: 
– Digg 
– Reddit (all button styles) 
– Delicious 
– Sphinn 
– Dzone (all button styles) 
– StumbleUpon
<h4>For Your Posts</h4>
Use the following in your posts: [SB button 1, …, button N]
Here’s an example post…
<pre><code>Hey, check out my new buttons!
Here they are: [SB digg, delicious, reddit]
And look
Here's some more:
</code></pre>
 [SB reddit, sphinn]
The different button types are: 
– digg 
– delicious 
– reddit 
– reddit1 (same as reddit) 
– reddit2 
– reddit3 
– sphinn 
– dzone 
– dzone1 (same as dzone) 
– dzone2 
– stumbleupon 
– stumble (same as stumbleupon)
<h4>For Your Themes</h4>
<pre><code><?php echo sb_make_button('digg', 'http://www.alexpooley.com') ?>
<?php echo 'I'm in a post now:'.sb_make_button('reddit', get_permalink()) ?>
</code></pre>

Social Buttons

Selectively add social network buttons to your posts, or theme design.

Share Rail vs Social Buttons