One of the most visited blog is http://Problogger.net
As for as I am concerened, I can't do without it.
The blog is about blogging, blog marketing, blog design, make money from blogs, case studies, interviews, SEO tips, content writing, blog tolls and so on and on and on.
You should visit once to believe what I am saying.
This blog is operated by Darren Rowse, an Aussie, blogging since 2002.
He is my inspiration and motivation.
Visit now: http://problogger.net/