AffiliateWP - A powerful affiliate marketing solution for WordPress.
DISQUS - Disqus is a global comment system that improves discussion on websites and connects conversations across the web.
ReferralMagic - Turn your users and customers into referral magnets.
Commento - A fast, bloat-free comments system to foster discussion on your website
Everflow - Partner Marketing Platform - Track, Analyze & Automate
utterances - A lightweight comments widget built on GitHub issues.