There's a big discussion going on now among SEOs (search engine optimisers) about Google's pronouncements about paid links. Basically Google has banned them and promised penalties for using paid links. This is a kind of totalitarianism - Google is free to do what they want with their own algorithm but that does not give them the right to dictate how and when you should advertise.
People have been warning of an impending Google oligarchy and it seems to be coming true faster than planned.
There is some confusion about how much Google knows about your website and your incoming links. Don't be confused.
A site called Touchgraph.com will show you a lot about what Google knows about your vertical in a java application which loads directly in your browser.
Touchgraph runs off of the similar pages data in the Google serps's (look for it).
Particularly useful is the simplicity - click on a link and see the home page in a new window.
What is frightening in the new Oz is that Google has much better technology behind the curtain. I'm sure Google has a similar chart but with the spam and trust numbers for each website popping up. As they analyse a single vertical forensically, to improve the SERPS (at this point that's pretty much what they'd have to do, as SEO spam is getting better), they can apply the algorithm tweaks across dozens of verticals hypothetically. If they like what they see, new algorithm gets rolled out.
Even as a client you will find it interesting to plug in your key search terms and have a look at the results. Who is in your group?
Ideally you'd want a link from nearly every site in the vertical to your website.