At the outset of The Great Cat Massacre , Robert Darnton cautions that "I do not believe there is such a thing as a typical peasant or a representative bourgeois."
There is no typical weblog. Nor can you study a set of "randomly-selected weblogs." A specific weblog is interesting only because that specific writer has something specifically interesting to say.
The average book, the typical hypertext, and the average weblog are all purple cows.
Thanks to Torill for identifying the issue.