TIgor4eg

Plugin shows <a href="http://www.twitter.com" rel="nofollow ugc">twitter</a> links from <a href="http://backtweets.com" rel="nofollow ugc">backtweets.com</a> in widget area.
<a href="http://tigor.org.ua/wp-twitbacks/" rel="nofollow ugc">Russian description</a>
It shows “shortened” links like bit.ly, goo.gl and other link shortering services.
You can configure your widget.

WP Twitter Backlinks

Plugin shows twitter links from backtweets.com in widget area.

wphobby

<h4>Tunnels</h4>
The main function of this is to publish your wordpress post to social medias, you’ll need a API key to enable this plugin.
More info:
<ul>
<li><a href="http://www.tunnels.me/" rel="nofollow ugc">tunnels</a></li>
<li>Read more great <a href="http://www.wp-coder.net/blog" rel="nofollow ugc">WordPress tips</a></li>
</ul>

Tunnels

Post on your twitter and facebook account when you publish a new post, which will take many backlinks to your site.

WP Twitter Backlinks vs Tunnels