Chrome only: Extension Don't Break the Chain tracks your progress with Jerry Seinfeld's productivity secret — a calendar that tracks how many consecutive days you've successfully achieved a certain goal.
All the extension really does is bundle up the calendar from previously mentioned web app Don't Break the Chain and move it into an easy-access button on your toolbar, but it's a great way to keep yourself productive without a lot of effort. Simply click the box for each day you complete a task, and skip the days you don't — the app will tell you when you've been dropping the ball. Don't Break the Chain is a free download, works wherever Google Chrome Extensions do.
Don't Break the Chain [Google Chrome Extensions]