When I'm requesting higher authority site that similar to my niche for submit a guest post. They agreed to give one no follow link in author byline. That site domain older more than 3 years and has Google PR 6 and Alexa rank 20,000 with more than 250,000 daily page preview and I think most of them come from Google. So is it useful thing submitting a guest post to that site for get a no follow link? This site not related to blogging, SEO, web designing. So their actual Alexa rank should be more higher than current level (i guess actual rank between 10,000-14,000 ). Because of this field (financial) people not highly use Alexa toolbar. I'm not expecting to drive traffic to my blog via guest posting. I use guest posts to improve my site SEO & SERP. Thanks!