You can find following add-ons in the Third-Party Add-ons section of the Add-on store:
Disqus comments for EPiServer CMS
Disqus comments for EPiServer CMS add-on contains core components that allow to add comments on EPiServer CMS pages using content properties, blocks or by injecting resources in certain rendering areas. This add-on should be installed on public servers.
EPiServer 7.x.x CMS, Add-on system. (EPiServer.Packaging).
Both MVC and WebForms are supported. Patch 3 is required to enable comments block rendering on MVC site based on EPiServer 7.
Disqus comments configuration UI
Disqus comments configuration UI add-on provides user interface that allows to configure Disqus comments on a website. Also it contains Edit UI extensions that help to work with Disqus blocks when editing a content. Install this add-on on a server where Edit and Admin UI is deployed.
EPiServer 7.x.x CMS, EPiServer UI Platform (Shell). Both MVC and WebForms are supported.