My biggest issue of late is how does google weight certian factors to determine relevance? How much of it is content and how much of it is links coming into that site? Have there been any tests into this?

Another item I have been trying to determine is how google group sites. In other words what sites are relevant to what. You can say that both sites are financial, but that is a large scope. There has to be some type of hierarchy that we can agree on for link building purposes. Its hard for me to decide which sites are the most relevant image google with their million factors and filters trying to figure out what is really relevant for every possible thing in the world.