Ask HN: How do you advertise niche blog sites?

While developing web apps, I'm looking for a quick and passive way to make money on the side (who isn't?). I've heard some talk about building niche blog sites and monetizing with Google Adsense, but relatively few details on how this is actually done. From what I've gathered, the general process goes something like this:

1) Use Google's keyword tool to find a topic with decent traffic but low competition.

2) Create a basic wordpress site around the topic.

3) Hire ridiculously cheap freelance writers to compose perfectly written, relevant content around the topic.

4) Make money from Adsense.

I've created plenty of websites in the past, and this just seems too easy. In my experience, a website with good content just wont cut it. Marketing that website is a full-time job. I have never seen a website just float to the top of Google with virtually no marketing efforts, so something seems to be missing in this formula. Kreci[2] mentions paying for backlinks, but I understand that this is looked down upon by Google.

So how is it done? What's missing here? Does the magic lay in the keyword tool itself? I realize that the keyword tool gives you keywords that are ideal for something like this, but how do you beat the competitors for those keywords?

Some how-to's:

[1]http://www.youtube.com/watch?v=1merER1zVFg

[2]http://www.kreci.net/freelancing/how-to-outsource/