From Seth Godin:
A lot of people have blogs. But most people don't.
I think you should. Even if you only have one post in you.
Having a blog is pretty daunting, especially if you don't like blank paper and are the sort of person that hates falling behind. I can imagine that the idea of posting 50 or 300 times a year is a little bit nuts for many people.
But what if there's just one thing you need to say, but you can say it clearly and well and in a way that hasn't been said before? What if you've got one great blog post inside of you, and, even better, you're willing to update that post as you learn more and gain more insight?
An entire post about a certain kind of fossil. Or the misuse of a certain word. Or about a key difference between two kinds of bluetooth...