Commit Together by Github - Now add co-authors to your commits
GitZip - Download or create a download link for a GitHub project folder/sub-folder or file.
GitKraken - The intuitive, fast, and beautiful cross-platform Git client.
Refined GitHub - Browser extension that makes GitHub cleaner & more powerful
Source iOS - The best git client and code editor for iOS.
GitHub Hovercard - GitHub Hovercard provides neat hovercards for GitHub.