DISQUS - Disqus is a global comment system that improves discussion on websites and connects conversations across the web.
Reddit - Reddit gives you the best of the internet in one place. Get a constantly updating feed of breaking news, fun stories, pics, memes, and videos just for you.
Quuu - Quuu is a curated content suggestion platform that connects to your Buffer queue, allowing you to grow a relevant social media following across your entire social landscape.
Facebook Comments - Facebook comments plugin lets people comment on content on the site using their Facebook account.
Written - Written helps content marketers build their audience by licensing content and audience from bloggers.
Discourse - Discourse is an open source discussion platform built for the next decade of the Internet.