I've been using the pomodoro technique for over three weeks with great success. I was skeptical, b/c I've tried similar techniques before, with much less success. Previous to this test, I was doing 90 minute chunks of work, which evidently made it much easier for me to burn out. My own details/log are here.

The pomodoro cheat sheet is an excellent summary of the technique, for those interested.

I switch between using a pomodoro app and e.ggtimer.com/25minutes. I plan/track my pomodoros weekly using mind maps.