While reading a software blog, I came across a reference to the Pomodoro Technique for increasing productivity. The basic idea is that you set a timer for 25 minutes and just do the items on your to do list for that time period, hopefully without interruption. If interruptions, arise, you jot them down, then go back to the main task. You can read about the technique here: www.pomodorotechnique.com. It recommends that you use and actual timer and paper, but I still like using software and the best application that I've found is Pomo Time (www.xoring.com) because it mimics the recommended paper very well.
If you're trying to get through NaNoWriMo (I'm not, I just like being more productive) or just want to help your productivity and concentration, give this simple technique a try.