Garth Gutenberg

Lets you display a twitter feed in a sidebar widget. 
Caches last successful tweet retrieval and only updates if it successfully gets a new list from Twitter. 
Practically every element has a unique class so that it’s highly customizable via CSS.
There are various configuration options including:
<ul>
<li>Title</li>
<li>Twitter Username</li>
<li>Max Tweets to Display</li>
<li>HTML to override the View All link</li>
<li>Time Placement (whether or not the timestamp should appear before or after the tweet)</li>
<li>Time Format (uses PHP’s date() function for formatting)</li>
</ul>

GG Twitter

Curtiss Grymala

Adds an available widget to list various social media profiles. The following social media sites are included by default:
<ul>
<li>Facebook</li>
<li>Twitter</li>
<li>YouTube</li>
<li>LinkedIn</li>
<li>Google+</li>
<li>FriendFeed</li>
<li>Flickr</li>
</ul>
This plugin also includes a filter hook allowing you to extend the available services.
By default, this plugin outputs an unordered list (ul) with a class of <code>social-icons-list</code>. Each service is output as a list item (li) with the service name used as the HTML class attribute. Filters are available to allow you to change those HTML elements.

Social Icons Widget

A developer-friendly plugin that allows you to add a widget with links to various social media profiles.

GG Twitter vs Social Icons Widget