maltpress

This is a simple Twitter widget for your sidebar. I know there are several out there, but I needed something very specific for my site and decided to make it a bit more general and release it into the world…
This plugin uses basic caching so you don’t hit the API rate limit (it’s using the user.timeline API method rather than the deprecated RSS method). It will need to write a (small) xml file to your uploads folder, and to update this regularly, so make sure the directory is writeable. The cache time can be changed for busy sites or quiet sites where you want more immediate effect – but the default updates every minute (if required, it won’t be active if no-one’s on your site) so you should be fine.
User controls:
<ul>
<li>Title: widget title</li>
<li>Twitter user name: feed to show (must be public)</li>
<li>Cache time: put this up for really busy sites, but you probably won’t need to</li>
<li>Show replies: show tweets which are @replies (won’t remove tweets which mention someone)</li>
<li>Show “via” link: shows your tweet method (i.e. “Via Tweetdeck”) with link</li>
<li>Tweets to show: number of tweets, up to 20 (with @replies on – see FAQ)</li>
</ul>

Reet-pe-Tweet

Simple Twitter widget for sidebars. Show/hide @replies & "via" links. #tags link to Twitter search, @names link to profiles.

wptwitterplugin

Simple Twitter Widget for WordPress

Reet-pe-Tweet vs WP Twitter Plugin