Back in mid-December, SEOmoz made a number of changes to our use of the rel="nofollow" tag on the internal link structure of this site. We nofollowed dozens of links on many of our template pages to help control the flow of link juice through to our more important pages - the content in the Blog, YOUmoz, Marketplace, and Articles.

SEOmoz's Blog with Nofollow Links Highlighted

As you can see, we used quite a few nofollows to help draw juice away from unnecessary pages. The results?

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A resounding success! While you can see that search referrals were particularly slow at the end of December and into January (as was overall site traffic), once the holidays passed, the search traffic came rolling in. The bump is approximately 20%, quite a substantial rise from the addition of a tag on some less important links.

While others have certainly reported seeing success with the use of nofollow to control the flow of link juice, I figured this quick example might help serve as a catalyst for anyone who's skeptical about the potential value.

BTW - I do certainly realize that many other factors could have affected increased search referral numbers, and thus this test isn't entirely scientific. However, our search traffic going all the way back to May of 2007 was increasing at an infintessimal rate (Weeks 20, 21, and 22 of 2007 [May-June] had an average of 12,000 search referrals) and this is the only structural change we've made since that time. Thus, don't take this data as gospel truth, but rather as another nudge that nofollow sculpting can have high potential rewards.

p.s. We have done used this same thing on projects for clients with mixed results - several have seen increases of 20-25% in 2-4 weeks, but one of our clients stayed virtually level after implementation.

p.p.s. For more on how sculpting PageRank with nofollow works and why it can be effective, see Si's excellent post on the subject .