Hi Forum Guy,
I'm totally new here. I'm in a similar situation as you, where I have to set my own direction and hold myself accountable for my progress.
I'm assuming you're doing intellectual work of some sort (writing, design, programming, studying) - for that type of work, the single key to productivity is "flow". Mihaly Csikszentmihalyi has a whole theory around it, but it boils down to setting things up so that you feel an optimal level of challenge, not too hard, not too easy. Too hard, and you bail. Too easy, and you lose interest. And, most importantly - no distractions and interruptions.
The thing about flow is that it takes about 15-20 minutes to get into it, your brainwaves have to synchronize I guess, but losing your flow happens much more easily, like someone asking you an unrelated question, or a new email that pops up, etc.
So, you should stop multitasking, and every time the urge to do some insignificant side task comes up, you should remind yourself of what you really should be doing. If you don't have a clearly defined "next action" then you need to sit down and break down your amorphous tasks into discrete chunks that you can handle in 5-15 minutes.
If you're so automated in your forum checking habit, then cut your Internet connection or block the sites you frequently check. The failing connection will help you snap out of it. Or do some work away from the computer if you can. Also, force yourself to do some real work and use going on a forum binge as a reward for having done something real.
Also remind yourself of whether what you're doing right now will get you anywhere in the future, in terms of success or meaningful experience. Reading blogs/forums can be like eating junk food - a quick satisfying high, but over time it doesn't do you any good.
Also, don't think you should be working all day. It's amazing how much work you can get done in three hours of flow/complete focus.
Adjusting your diet, sleep patterns, and exercising can also help you focus better.
I hope this makes sense and is practical. If not, please elaborate why exactly you think you're procrastinating (not knowing what to do, not liking it, seeking immediate gratification, etc.).