Speedboxer

<p>This plugin will convert valid <a href="http://twitter.com/" title="Twitter" rel="nofollow ugc">Twitter</a> usernames mentioned in comments into a link to their Twitter profile page. For example, if somebody mentions “@mattfreedman” in their comment, this plugin will check with Twitter to see if the user “mattfreedman” exists (which is does) and when it does, it will convert it into “<a href="http://twitter.com/mattfreedman" rel="nofollow ugc">@mattfreedman</a>“.</p>
<p><strong>Please note: As this plugin converts usernames on the fly (<em>whenever and everytime</em> somebody views the comments), and checks Twitter for every username (to ensure it’s valid), I <em>strongly</em> recommend using a caching plugin such as <a href="https://wordpress.org/extend/plugins/wp-super-cache/" title="WP Super Cache" rel="ugc">WP Super Cache</a>. Which will not only lessen the load on Twitter’s servers, but also speed up page loads.</strong></p>
<p>Although it says this plugin requires WordPress 2.6, I see no reason why it wouldn’t work with earlier versions, I just haven’t tested it with earlier version.</p>
<p><em>This plugin requires cURL to be installed on your server, and has only been tested with PHP 5.2.x.</em></p>


Twitter Links

Converts Twitter usernames mentioned in comments (eg. @mattfreedman) with a link to the mentioned user's Twitter profile page.

Jon Bishop

<p>Commentwitter is a WordPress plugin that gives commenters the option of Tweeting their comment with a link to your post. The plugin adds a new link next to the reply link in a comment that gives readers the optjon of tweeting that comment. This is a great way to bring the conversation from you blog on to Twitter and vice versa.</p>
<h4>Other features</h4>
<ul>
<li>Automatically creates bit.ly to specific comments in a post</li>
</ul>
<h3>Version history</h3>
<p>The current version is 2.1 (2010.11.16).</p>
<h4>2.1 (2010.11.16)</h4>
<ul>
<li>Added class=”comment-reply-link” to tweet link</li>
</ul>
<h4>2.0 (2010.11.16)</h4>
<ul>
<li>Removed ability to tweet new posts</li>
<li>Removed ability to automatically tweet posts from comment form</li>
<li>Added link next to ‘reply’ link in comment to tweet comment</li>
</ul>
<h4>1.5.2 (2009.10.06)</h4>
<ul>
<li>Switched from Cligs to Bitly</li>
<li>Removed Cligs API form from Admin</li>
</ul>
<h4>1.5.1 (2009.08.03)</h4>
<ul>
<li>Changed some javascript to fix functionality</li>
</ul>
<h4>1.5 (2009.08.02)</h4>
<ul>
<li>Added Thesis support</li>
<li>Fixed javascript toggle issue</li>
<li>Fixed “Send To Twitter” HTML</li>
<li>Changed Author URL</li>
</ul>
<h4>1.4.2 (2009.06.24)</h4>
<ul>
<li>Fixed URLEncoding issues</li>
</ul>
<h4>1.4.1 (2009.05.12)</h4>
<ul>
<li>Fixed some links</li>
</ul>
<h4>1.4 (2009.05.01)</h4>
<ul>
<li>Added help button and donation link</li>
</ul>
<h4>1.3 (2009.05.01)</h4>
<ul>
<li>Site owner can add a prefix to Tweets</li>
</ul>
<h4>1.2 (2009.04.30)</h4>
<ul>
<li>Tweet is only cut off if under 120 characters</li>
<li>Blog owner can now Tweet new comments automatically on own profile</li>
</ul>
<h4>1.0 (2009.03.05)</h4>
<ul>
<li>Released</li>
</ul>
<h3>To do</h3>
<ul>
<li>Auto approve comments when using CommenTwitter</li>
</ul>


Commentwitter

Gives commenters the option of Tweeting their comment with a link to your post.

Twitter Links vs Commentwitter