Pole Position Marketing did an excellent writeup on some link building secrets from 12 link building type people, including Rand Fishkin, Hamlet Batista, Jim Boykin, Debra Mastaler, Bob Gladstein, and Michael Gray and published the findings in a 24 page PDF.
Here's part of one tip (you'll have to read the PDF to get the rest of the tips):
Not all links are created equal. We know that some links help more than others in getting high search engine rankings. For some time now, link builders have primarily relied on Google’s toolbar PageRank as a good measure of the quality of a link. Higher PageRank values were ostensibly better than lower ones. Unfortunately, Google has played so much with the PageRank values it displays that it has become increasingly less useful.
Forum members are finding this information incredibly useful and actionable, so take a read.
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