Today at work I accomplished roughly twice as much in the last three hours of the day as did I did for the five hours preceeding it.
Granted, this was partially because two of those five hours were spent in meetings, which are unproductive at the best of times. But the rest of the enhancements were due to a very simple Firefox extension. What does it do? It blocks all the websites I like. In fact, on its own it doesn't even do that. I had to tell it what sites I like so it could stop me from visiting them. Of course I could accomplish the same effect by simply not visiting those sites, but that's so much harder than not being able to visit them. Some might call this self-deception; I prefer to think of it as enforced motivation.
In general motivation isn't an issue, but I've found that when I'm not sure how to approach a task, but also don't want to "jump right in and work it out on the way", I can often start thinking about it and somehow wind up on Digg. A little helpful reminder in the form of a blank page and an error message speeds up the "thinking" process immeasurably.
I also found a handy little program that allows you to save sequences of keystrokes and write them out at certain times (such as when you press a keyboard shortcut). It's great for little things like typing out your username and password, which I can now do with a single shortcut! Yes I know, I'm a geek. And a lazy geek at that.
If your "thinking" also causes you to traverse a large portion of cyberspace, you can get BlockSite for Firefox here, and the AutoHotKey macro recorder is available here.