Refined GitHub - Browser extension that makes GitHub cleaner & more powerful
OpenGrok - OpenGrok is a fast and usable source code search and cross reference engine.
GitZip - Download or create a download link for a GitHub project folder/sub-folder or file.
GrepCode - GrepCode.com is a code search engine built by developers for developers to search and browse open...
GitHub Hovercard - GitHub Hovercard provides neat hovercards for GitHub.
Krugle - Krugle is the complete enterprise solution for search targeted to the development organization.