Matt Blumberg tells us why he has found blogging useful.
I like his first reason - Thinking
One of the best things publishing a blog has done has been to force me to spend a few minutes here and there thinking about issues I encounter in a more structured way and crystallizing my point of view on them. Invaluable, but mostly for me.
I have never thought about it that way, but that's a big part of the attraction for me too.