Chrome: The Pomodoro technique is a great way to keep yourself on task and if you spend a lot of time in Chrome, TimeDoser is a great app to help you along.
We've featured apps on other platforms like Windows, Mac, Android, and iOS, but Chrome is lacking. TimeDoser is an offline Chrome apps that records time in 25-minute blocks with a five minute break. While you can't set an exact timer, you can change the interval to 30,35 or 40 minutes. You can change the break times to 10 or 15 minutes. Hit the link to try it out.