I recommend this entire article by David Carr which does a good job of analyzing how citizen journalism works on the web. Influence does not belong to anyone with a blog. It belongs to committed experimenters with passion and discipline. Like the people at Pitchfork.
NY Times: Garage Rock Meets Garage Critics by David Carr
The nexus of influence has shifted in the last few years. Destroying someone's career or pulling work from obscurity used to be the province of well-financed mass and trade publications, but now anybody with a voice strong enough to stand out on the Web can have a real impact - and maybe make a couple of bucks in the process.