My blog has a several pages that contain both information on a specific subject as well as links to several companies related to the particular subject. For each link, I have included the rel=nofollow attribute.
I do not seek-out the companies, nor do they come to me. I do not get paid for the links. They are strictly for information and references related to the subject.
Google's Webmaster Guidelines states that buying or selling links that pass PageRank is considered a link scheme, which can negatively impact a site's ranking in the search results. Their suggestion is to add a rel="nofollow" attribute to the <a> tag to prevent PageRank from passing.
So this got me thinking: will the rel=nofollow tag I have attached to my links raise a red flag with Google? I realize they may penalize me if I don't have the nofollow, assuming I am selling links to pass PageRank. But what if they see several links with the nofollow...will they see this as selling links and penalize me?