Ebook Sample Content Preview:
There is no trick to it, nothing black hat. Just simple content sites with relevant links and tags. You are pretty much just creating sites that Google asks you to create in it's FAQ section about getting your site listed in their search engine.
I've only ever used unique content I've written or a ghostwriter has written to make my content sites. I'm not a fan of duplicate content or non rewritten PLRs.
I'm sure this method would work with non unique content, but you have a better chance with unique content. Plus then you own a completely unique site on a new niche topic.