godthor

This will create a new widget which will display your most popular posts and pages based on comment count with Disqus. Alternatively, you can use a shortcode as well.
It’s very simple to use. Just drag the widget into a sidebar and configure it, or visit the settings under the WordPress Settings menu.
Just Some of the Options:
<ul>
<li>Show featured image.</li>
<li>Choose featured image size.</li>
<li>Choose featured image alignment.</li>
<li>Show the post date.</li>
<li>Select how many days to check, IE: past 90 days.</li>
<li>Set how many posts to show.</li>
<li>Save the results for faster loading.</li>
<li>Load results using Ajax. Perfect to avoid caching results.</li>
</ul>
Note: This plugin requires you have an application registered with Disqus: https://disqus.com/api/applications/ 
It’s free and simple to setup, just follow that link.

Disqus Popular Posts

Creates a widget to show the most popular posts and pages on your site based on Disqus comments. Can also be used with a shortcode.

Automattic

Glenn Ansley

This plugin will import comments from a Disqus export file.
Due to a limitation with the current version of the Disqus Comments plugin the import does not retain nested commenting. Once this support is available in the XML, we will provide support.
Please provide feedback and bug reports in the <a href="https://wordpress.org/tags/disqus-comments-importer?forum_id=10#postform" rel="ugc">Forums</a>

Disqus Comments Importer

Import comments from a Disqus export file.

Disqus Popular Posts vs Disqus Comments Importer