I just started using GTD-like techniques. The basics of it are this: (1) write everything down as you think of it, so you don't forget anything. (2) very often, go through the list of random items; do the small (two minute) tasks immediately, and organize the rest of them into into (groups of) "next actions." (3) spend all the rest of your time eliminating items from the "next actions" list.
I think it is effective. There were many times when I let a lot of email pile up in my inbox. Now, I very deliberately go through my email and respond to everything ASAP; everything that I can't do immediately gets filed away in a TODO list so I don't forget it. My inbox is thus ALWAYS empty. I don't know why but that makes me happy. It also makes other people happy because they are getting their responses faster. And, I get more done because having a list of "the next thing I need to do" makes me want to do things to get them off the list.
The other thing I found to be helpful is to schedule all my distractions. Now, I have a reminder that tells me "hey, check your email" and even "hey, check your feed reader." This seems silly, but it is really helpful; I know that I will get the "check your feed reader" reminder soon, so I just keep working until it comes. Sometimes, I get annoyed and refuse (!) to check my email because I'm busy; in fact, I had started with scheduling them hourly but I am slowly reducing it down to three times per day. As a result, I check my email and weblogs WAY less frequently than I did before (even with an hourly reminder), because before I would check my email basically in between each item on my TODO list or even in the middle of something.