A blog works by starting and participating in conversations.
It is pretty much exactly like what you do when you are with a group of people and join in real life conversations. Sometimes you find people ignore you but, if you peak their interest, they will sometimes get really engaged. And, in the process of getting to know you, they naturally learn what you do and offer.
With comment systems, track back links, and the social networking Web 2.0 services, you can rather innocuously and genuinely become part of a conversation and increase your exposure. Sometimes an entry won't generate much traffic. But other times you can infect a viral marketing epidemic. You will certainly generate more exposure than you would otherwise.