This is a simple little distraction management system I've been practising for a couple of months or so.
Take a red post-it and write down the names of three (or so) websites that are constantly distracting you. Then draw a slash through them. These are your anti-bookmarks, your index of prohibited sites. When you are busy and want to focus on a task without distraction, affix the post-it to your monitor. Do not visit these sites while the post-it is attached. When you are done focusing (say, at the end of the work day) take down the postit. You are now free to visit these sites.
I'm amazed at how well this works, with just three sites (slashdot, nytimes, fidelity). These are the sites I almost automatically go to to procrastinate. Apparently, I find it difficult to procrastinate without going to one of these sites (because going somewhere else would involve a level of intentionality that is inconsitant with the nature of procrastination). By eliminating these procrastination points during peak attention hours, I essentially eliminate procrastination. I would never have guessed that so much (virtually all) of my procrastination went through these three sites. I knew they were biggies, but I figured I'd just divert my traffic through other sites, or that I'd find replacements. And I'm sure I could, if I tried. But procrastination is a lazy thing, and making yourself have to try is enough to avoid trying.
I keep the anti bookmarks up at work the whole day, so that postit just stays there. At home I take it up and down as needed. I think one of the keys to making this work is to keep the list very, very short (so you can cache it in memory for rapid retrieval

Reinhard