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.

Phoenixheart

“Digg This O’ Mine” is a plugin that allows you to place the famous <a href="http://digg.com/tools/integrate" rel="nofollow ugc">“Digg This” button</a> at the end of your posts, pages, or anywhere at your choice. While it will run out of the box, it has several options that can be used to custom the button to fit your needs:
<ul>
<li>Automatically add “Digg This” button to your posts (yes/no). Default is set to Yes.</li>
<li>Automatically add “Digg This” button to your pages (yes/no). Default is set to Yes.</li>
<li>Background color around the button. The option is provided with a handy color picker. Default is “#ffffff” (white)</li>
<li>Skin of the button. Digg offers 2 skins: Default and Compact. Default is set to “Default” 😉</li>
<li>Open the Digg link in a new window (yes/no). Default is set to No.</li>
</ul>

Digg This O' Mine

Place a "Digg This" button at the end of your posts, pages, or anywhere at your choice.

Share Rail vs Digg This O' Mine