Aaron D. Campbell

A widget that properly handles twitter feeds, including parsing @username, #hashtag, and URLs into links. It supports displaying profiles images, and even lets you control whether to display the time and date of a tweet or how log ago it happened (about 5 hours ago, etc).
<a href="http://aarondcampbell.com/wordpress-plugin/twitter-widget-pro/" rel="nofollow ugc">Twitter Widget Pro</a>

Twitter Widget Pro

A widget that properly handles twitter feeds, including parsing @username, #hashtags, and URLs into links.

Christopher Shennan

This plugin displays the twitter posts from a twitter account in the sidebar.
wpTwit is a PHP Twitter Reader based on <a href="http://www.chrisshennan.com/my-projects/linetwit-a-php-twitter-reader-based-on-mytwit/" rel="nofollow ugc">lineTwit</a> which was written for <a href="http://www.line.uk.com" rel="nofollow ugc">Line Digital</a> and based upon <a href="http://www.axllent.org/projects/mytwit" rel="nofollow ugc">myTwit</a> by Ralph Slooten.
wpTwit was written by <a href="http://www.chrisshennan.com" rel="nofollow ugc">Chris Shennan</a>.

wpTwit

Add your twitter posts to your blog using wpTwit - A PHP Twitter Reader based on lineTwit (an extension of myTwit by Ralph Slooten)

Twitter Widget Pro vs wpTwit