I think that sometimes people see articles as a way to boost traffic, and then everything else is a function of the traffic. So they have two things happening here: 1) write articles, get traffic 2) Sell to traffic, etc.
But I see it differently. You see, I have written around 300 articles and have about 100,000 words of content just laying on my hard drive, bored out of its mind.
So I not only use articles to boost my initial traffic, but I use them to boost my affiliate revenue.
Here are the things I use my articles for to boost my affiliate revenue:
1) I use my articles in my email campaigns to build credibility and make sales
2) I bundle 10 or so articles together from time to time and send my subscribers a free ebook.
3) I sell the rights to my articles
4) I send my subscribers to my articles for additional content for them
5) I use my articles for bonus material when I write my new ebooks