Refined GitHub - Browser extension that makes GitHub cleaner & more powerful
KeyCue - Menu shortcuts are supposed to provide quick access to frequently used menu commands.
Octoview - The missing preview feature for GitHub
CheatKeys - View Windows keyboard shortcuts in the current application.
Dyllo - A clean and simple way to view a Github user's information
cheat - Cheat allows you to create and view interactive cheatsheets on the command-line.