Gitstalk - Discover what your favorite GitHub users are up to
GitZip - Download or create a download link for a GitHub project folder/sub-folder or file.
Octoview - The missing preview feature for GitHub
Refined GitHub - Browser extension that makes GitHub cleaner & more powerful
GitNews Web - Trending repositories from GitHub, HackerNews & Reddit
GitHub Hovercard - GitHub Hovercard provides neat hovercards for GitHub.