Softagram - Automated visual reviews for GitHub pull requests
GitHub Visualizer - Enter user/repo and see the project visually
CodeTriage - Help out your favorite open source projects and become a better developer while doing it.
Codeology - Open-source algorithm that visualizes GitHub projects
BountySource - BountySource is a funding platform for open-source bugs and features.
Octohunt - Search to find developers in your city on Github.