Refined GitHub - Browser extension that makes GitHub cleaner & more powerful
Dyllo - A clean and simple way to view a Github user's information
CodeBottle - MIT-licensed reusable code snippets
GitHub Hovercard - GitHub Hovercard provides neat hovercards for GitHub.
SyntaxDB - Easily look up programming syntax for multiple languages
DownGit - Directly download or create download links to GitHub public folders or files.