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There are only three reasons to no-follow a link, Tom. The link is untrusted - e.g. User-generated content like blog comments or forums The link is being paid for or is otherwise part of a business arrangement (this is a little broader - can include large-scale guest-posting and press releases) In specific cases to help manage crawl budget for a site (note: NOT to be used to try to manage flow of "linkjuice" internally through a site) Anything other than these uses could actually cause overuse of no-follow to make your own site look spammy/questionable. Here's a really good overview post from Raven Tools blog on exactly the question you're asking about what constitutes effective, safe use of outbound links. Hope that helps? Paul