Apple App Analytics - Apple's very own iTunes Connect App Analytics
GitHub Team Discussions - Now there's more space to talk through your projects 💬
My Motiff - Allowing you to stay connected in realtime
Schnack - Schnack is an open source commenting system written in JavaScript.
Usage Analytics in appFigures - Track usage for your app along side downloads, ranks & more
Product Hunt Reviews Widget - Embed and encourage PH reviews into your product