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

Simivar

Adds a sidebar widget to display Twitter updates (using the Javascript). You can set number of messages, color and other features.
You can change colors of shell background and shell text; tweet background, tweet text and tweet link. You can set on/off a features like scrollbar, show hashtags, poll for new results, show timestamps/avatars and the behavior.

Advanced Twitter Profile Widget

Adds a sidebar widget to display Twitter updates (using the Javascript). You can set number of messages, color and other features.

GG Twitter vs Advanced Twitter Profile Widget