My approach is simple and is inspired by the No Meat Athlete and Zen Habits blogs. I first make a list of things that need to be done. It can be large or small; it doesn't matter. I then work on one thing on the list and only open programs and browser tabs that directly relate to this task. That's the most important part. Multitasking, I've decided, is the bane of productivity.
If I see an interesting paper, I use Instapaper to save it for later. If I have too many e-mails or unread items, I go through and delete the ones that were once relevant but no longer are. The goal is to reduce the noise and possibilities to be distracted while working. This also includes choosing not to listen to music if I am writing anything or doing something that requires more than passive attention.
Of course, I also account for when I can not avoid being distracted. I allow time to be interrupted (and I will be numerous times) during the day by my colleagues and adviser. I also set time limits that are proportional to the magnitude of the task. If I have lab work, I give myself an hour minimum and two hour maximum; conversely, computer work is usually delegated 15 minutes to an hour. By setting upper time limits, I allow myself to be satisfied with unfinished work, knowing that when I pick it up again I will have a fresher mind. And by setting lower time limits, I ensure that I have enough time to accomplish something meaningful. Once an item on the list is done, I remove it. If it's not done, it stays.
This may be a bit too much micromanaging for some, but with the amount of things that are required of one in academia, I think it's necessary.
I believe that Henri Poincaré had habits similar to these. His goal, in part, was to maximize his creativity. I think this was so because he believed that a creative mind must be allowed to wander around different tasks. In this way, he recruited his subconscious to work on problems while he consciously worked on others.
