Gitter, chat for GitHub, is now public beta 12 years ago
Been using Gitter with my Dev Group for a few weeks and we all love it and switched completely to it as our main Chat. It's worth a try and the integration of services like Trello and - for sure - Github is just great! Also Auto-Embedded Links (YouTube, SoundCloud, images (jpg, png, gif)). Really love it and I'm looking forward to the apps. :)