If I had to guess, I would say that 95% of the BSOD's I've had were caused by me, as WYSIWYG said. And, there were times when I just knew that it was going to happen because of my impatience, or dumbness, or whatever.
The only ones I have had with Vista or Windows 7 were caused by a corrupted True-Crypt file. Had to have a couple of them before I figured out what was causing it.