Wiep Knol put together a fantastic document on internal and external linking values. Developed in the same format as Rand’s Search Engine Ranking Factors, Wiep’s Link Values Factors puts together some of the greatest minds in link building, presents them with a series of factors and asks them to rate each according to how much weight it carries.
As is usually the case, not everyone agrees, which is what makes this document fun. It’s very eye opening in that some of the top minds disagree so completely on what is or isn’t a valuable link. It only goes to show that there is still much to be proven in the science of link building. But you have to admire anybody who can definitely answer any of these questions at all. A lot of time and testing has to go into knowing many of these answers, and you know that even if in disagreement, these guys are well educated in the realm of links.
But the experts are more often in agreement than disagreement which makes this an extremely valuable document for learning and understanding the good and the bad of link getting. Of course, don’t confuse this with a how-to document, it’s not. You won’t learn any link building strategies or gain any insight in the process of getting good quality links. But what you will learn is what makes a quality link and what does not.