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.

geilt

Enables a widget that will pull a twitter feed feed via API by Twitter @UserName and display them.
Since Twitter updated to v1.1 OAUTH, Twitter Application credentials are now required to be registered to authorize use of the Twitter API.
<a href="https://dev.twitter.com/apps/new" rel="nofollow ugc">Create an Application</a>
<a href="http://www.esotech.org/plugins/simpul/simpul-tweets/" rel="nofollow ugc">More Details</a>

Simpul Tweets by Esotech

Enables a widget that will pull a twitter feed feed via API by Twitter @UserName and display them.

Twitter Widget Pro vs Simpul Tweets by Esotech