Most of us have a problem with procrastination. I could certainly argue (with real justification) that a majority of Facebook and Twitter's usage occurs when people are procrastinating.
Despite my wide array of productivity techniques, even I find myself procrastinating. Ironically, one of the main reasons I end up procrastinating is because I have trouble resolving the inherent conflicts within those systems.
For example, I like to have prioritized lists of things that need to happen. But the issue is, there is never a simple priority. As Stephen Covey pointed out, both urgency and importance matter. A particular task might not be as important, but as its deadline draws near, it gains in importance.
The problem gets worse with large and indeterminate tasks like "catching up on email" or "writing blog posts." Neither is necessarily more important than the other, and their relative priority flip flops depending on how much I've worked on them lately.
This morning, I had a pretty clear priority to either read email or write a blog post, yet I found myself spending about 5 minutes on the highly-addictive TVTropes.org because I couldn't decide which to do.
That's where Two-Face* productivity comes in. When faced with multiple tasks of roughly the same priority, the best technique is simply to choose one at random and start working. This blog post, for example, won the coin toss.
The reasons Two-Face productivity works is that the choice doesn't really matter--that's why it's so hard to make; you can't tell which choice is better. Rather than wasting time trying to logic your way to a decision (wasted time) or goofing off (really wasted time), a simple coin flip** or other arbitrary choice can cut the Gordian knot.
* Two-Face is the Batman villain who flips a coin to make decisions. I'm sure he has a much more depth to his characterization than that, but that's all I can remember from "The Dark Knight."
** If you really want to get geeky, you can also use D&D style dice for deciding between multiple options. As I recall from my childhood dice set, the standard D&D set comes with 4-sided, 6-sided, 8-sided, 10-sided, 12-sided, and 20-sided dice. For extra geekiness, you can roll a 10-sided die twice to get a random number between 1 and 100.