Most everyone who researches keywords already knows about Overture's Keyword Research tools (Or you can use SEO Kings Tool) and Word Tracker. However, if going it alone, these are some great resources to help you get started.
I can do the same for sub-prime, FHA, Hard Money, and any other topical mortgage related pattern I want effectively. This is KW analysis and maximizing KW patterns to the advantage of any site you build. It is not just how deep into the tree you go, but how many individual words you add...
Much of SEO blends together to make a pattern. What I present to you is a way to expand the ranking patterns of your sites. The logic of this is based on the fact that all numbers are patterns. When analyzing KW, the process I use relates specifically to word patterns.