Commentics - Commentics is an advanced PHP comment script with many features.
Epoch by Postmatic - A native WordPress Disqus alternative with a focus on speed and privacy: 100% realtime native...
RbComment - RbComment - Zend Framework 2 module for drop-in, self-hosted comments, with email notifications...
DISQUS - Disqus is a global comment system that improves discussion on websites and connects conversations across the web.
talkatv - talkatv is an open source comment service much like ...
Joint Comments - An embeddable comment widget for websites, blogs, ecommerce & static pages.