GitHub + Slack Integration - Full visibility into your GitHub projects right inside Slack
GitHub Visualizer - Enter user/repo and see the project visually
Cryotos - #1 Maintenance Management Software
Octohunt - Search to find developers in your city on Github.
Codacy - Automatically reviews code style, security, duplication, complexity, and coverage on every change while tracking code quality throughout your sprints.
Gource - Gource is a software version control visualization tool.