GitZip - Download or create a download link for a GitHub project folder/sub-folder or file.
GitHub Visualizer - Enter user/repo and see the project visually
Refined GitHub - Browser extension that makes GitHub cleaner & more powerful
Learn X in Y minutes - LearnXinYminutes isn’t a good way to learn your first programming language, but it’s a great way to...
GitHub Hovercard - GitHub Hovercard provides neat hovercards for GitHub.
Gource - Gource is a software version control visualization tool.