This idea has been mentioned in several comments, but it deserves a top-level post. From an ancient, ancient web article (1995!), Stanford philosophy professor John Perry writes:
I have been intending to write this essay for months. Why am I finally doing it? Because I finally found some uncommitted time? Wrong. I have papers to grade, textbook orders to fill out, an NSF proposal to referee, dissertation drafts to read. I am working on this essay as a way of not doing all of those things. This is the essence of what I call structured procrastination, an amazing strategy I have discovered that converts procrastinators into effective human beings, respected and admired for all that they can accomplish and the good use they make of time. All procrastinators put off things they have to do. Structured procrastination is the art of making this bad trait work for you. The key idea is that procrastinating does not mean doing absolutely nothing. Procrastinators seldom do absolutely nothing; they do marginally useful things, like gardening or sharpening pencils or making a diagram of how they will reorganize their files when they get around to it. Why does the procrastinator do these things? Because they are a way of not doing something more important. If all the procrastinator had left to do was to sharpen some pencils, no force on earth could get him do it. However, the procrastinator can be motivated to do difficult, timely and important tasks, as long as these tasks are a way of not doing something more important.
The insightful observation that procrastinators fill their time with effort, not staring at the walls, gives rise to this form of akrasia aikido, where the urge to not do something is cleverly redirected into productivity. If you can "waste time" by doing useful things, while feeling like you are avoiding doing the "real work", then you avoid depleting your limited supply of willpower (which happens when you force yourself to do something).
In other words, structured procrastination (SP) is an efficient use of this limited resource, because doing A in order to avoid doing B is easier than making yourself do A. If A is something you want to get done, then the less willpower you can use to do it, the more you will be to accomplish. This only works if A is something that you do want to get done - that's how SP differs from normal procrastination, of course.
Like most information works, I am constantly distracted by social networks - reading Twitter, blogs, answering email. I don't do these things because they are effortless and restful (that's what reading fiction is for), but because they feel like moderately productive work (learning new ideas about the world, keeping up on my ideasphere, connecting with people) that just so happens to be fun and easy. Unfortunately, that joy and ease translates into a distorted feeling about if/whether/how much I am accomplishing things. The marginal output product of my spending 15 minutes on social networks may be positive but it's close to zero compared to other kinds of work I could be doing.
SP suggests that I find other things which both feel like productive avoidance and actually are. For example, rather than reading blogs, I could read one of the dozens of books piled up that have been suggested as relevant to my areas of research. Yeah, that wouldn't be as much fun as digesting the clever little bites that are blog posts, but it still feels like avoiding the main unpleasant tasks, and it's actually important enough to be on my todo list (if not at the top).
Maybe this is just me applying my standard rationality themes everywhere, but I think that self-awareness and action vs. reaction are key to structured procrastination. When you are reacting to the vague feeling that you want to avoid doing something, you will automatically get driven towards quick and easy fixes - leave the report you are supposed to write in one window, and go to Google Reader in another. Anything to scratch the itch of avoidance.
But if you can have the self-awareness to notice your reaction of avoidance, you get to roll a saving throw about whether to make a conscious decision. If you pass, now you have a choice: buckle down, go with the distraction, or do structured procrastination? This choice opportunity doesn't automatically let you do the right thing - doing your primary task will still require a major expenditure of willpower. But at least it stops you from automatically doing the wrong thing, and gives you a chance to use akrasia aikido like SP to apply your willpower efficiently. Or perhaps go for a truly restful option like taking a break, going outside, or getting a drink, which actually rests your mind (and willpower muscle) much more effectively than looking at the latest on Digg.
There is more nuance to structured procrastination, but this post has gotten long enough already. If people find the topic interesting, I can write more about it's weaknesses and my ideas for addressing them.