The Insider. Aka 'Tales from the Inner Circle' or 'Preaching to the Ignorant'. If done well the readers join the circle of initiates (in their own head at least) while the author cements his place amongst the deeper mysteries.
The Jock. This relies on the force of the authors personality/wit/opinions to turn the everyday into the exceptional.
The One Trick Pony. Aka The Novelty Box. A Clever idea exercised repeatedly (ad nauseum?).
Aggregator-Curator. Done badly this is a list of other peoples work, done well it can be a sum that is greater than its parts.
The Wave Rider. Catch the moment to catch the audience, but probability makes most of these history by tomorrow/next week/next month.
Engineering. Geek-style, these weblogs push the technical envelope, sometimes at the cost of the content.
The Shopping Trolley. Browse for material enrichment from the comfort of your own keyboard, a good vehicle for web adverts too.
Under the Stone. Slice of life personal (and impersonal) diaries.
Postcards from an Edge (subclass). Extreme lifestyles and mindsets
Speaker Hiss (subclass). Nothing to see here except the minutiae of some drabs (inner) life, irrelevant for all but the closest of friends.
The Public Convenience. Aka Web-Two-point-zero. Providing the readership with a chance to generate their own content and take the pressure off the authors.
The PR Department. Officially sanctioned corporate mouth-pieces - often allied to The Insider.