I've started experimenting (dabbling) with the Pomodoro Technique to increase my productivity and ability to focus and stay on task. To oversimplify how it works, it's 25 minutes focused on a single task or objective, then 5 minutes break. Wash, Rinse, Repeat.
Benny the Irish Polyglot (of Fluent in 3 Months fame) uses the Pomodoro Technique and finds it useful especially for spaced repetition purposes.
If you don't have a red tomato kitchen timer (affiliate link), you can use the e.ggtimer.com utility. It's really handy and I use it often throughout the day.
Have you used the Pomodoro Technique? Have you found it useful?