Epoch - 100% realtime chat and commenting in a tiny little package that is fully CDN and cache compatible.

TechGasp Comments Master is the professional integration of facebook comments into heavy duty wordpress websites.

Conversational & Social Engagement suite for discussions without Trolls & easy reading. Keys to building a strong & engaged community. Add advanced discussion and community features on your website: Live discussion mode, Guest commenting, automatic registration with social connect, multi levels vote/reaction widget, inline media embedding and real-time notification center.

The WP Social Comments lets people comment on content (pages, posts etc) on your site using their Facebook account.

AJAX comment system. Insert and displays Comments easily and quickly using Ajax style of social networks.

This plugin will help you display Facebook Comments on your website. You can use it on your pages/posts.

Integrate Facebook Comments, Vkontakte Comments and/or Disqus Comments along with default comment form at your WordPress website