Mathias Gomig

Displays a simple widget with a list of the most commented posts.
<ul>
<li>English and German Translation</li>
<li>Number of Posts choosable</li>
<li>Multiple widgets possible</li>
<li>More Information will be added as the plugin gets better and bigger.</li>
</ul>
Features in the future
<ul>
<li>Choose year or period of time</li>
<li>Choose different posts types (Posts, Pages, …)</li>
</ul>

Most Commented Posts

Displays a simple widget with a list of the most commented posts.

Ron Zvagelsky

Integrates with the Disqus API to show your most popular threads (most commented posts). Can be added via sidebar widget, template tag, or shortcode.
<a href="http://presshive.com/plugins/disqus-popular-threads-widget-for-wordpress/" rel="nofollow ugc">For more information or to request additional features, please visit the plugin page</a>

Disqus Popular Threads Widget

Shows your most commented posts from Disqus via widget, shortcode, or template tag.

Most Commented Posts vs Disqus Popular Threads Widget