Commit Together by Github - Now add co-authors to your commits
GitHub Metrics - Customize your profile with various plugins and metrics
Commit Print - Posters of your git history
GitHub Contributions - All your GitHub contributions in one image
gitbird - So, I don't always remember to tweet what I do, but commit my code often, and what do users love more than your product?
Contributions for GitHub - Show your GitHub contributions graph on your iOS Devices