Shrink for Github - A macOS app for your Github issues
Refined GitHub - Browser extension that makes GitHub cleaner & more powerful
GitHub Reader - A quick way to browse GitHub issues and pull requests.
GitZip - Download or create a download link for a GitHub project folder/sub-folder or file.
Codetree - You can manage your entire development process through GitHub.
GitHub Hovercard - GitHub Hovercard provides neat hovercards for GitHub.