Never had an opportunity to use blogging to drive business directly, I have had a small amount of success in driving extra traffic to my site from blog posts, which may have in-directly brought in new work? I'm definitely interested to hear more on this as I'm hoping too make the blog more centered to my site focus with my upcoming site re-design.
I use blogging as my main source of traffic, most people think it is time consuming to create posts, then advertise them to get them noticed, which may well be the case, but it is my number one traffic source to my portfolio website, and when asked clients that I have worked with how they heard about me, it all came through my blog. Most of them liked my writing style and thoughts, which made them decide me. So I definately believe it is a tool most people should use. Especially when starting off.