Just getting into that now. There are two reasons I'm getting into auto-blogging. 1) To store landing pages to drive AdWords traffic to so that your landing pages are associated with many more pages of a site and thus increasing quality score to reduce cost per click and 2) to "sponsor" another site of mine that sells product.
So, in reference to #2, you bring in visitors to a topic related, auto-blog, and have on every page or the blog posts that the blog is sponsored by "x" company and have some special of the day.
By using an auto-blog feature, it would only take a matter of weeks before you could have literally hundreds of blog posts on google showcasing your "special of the day" with a link to your main ecommerce product selling web site.