Two of SEW forums' members, xan & orion, are currently discussing the value of several formulas, techniques & ideas that orion had brought to the SEO community. If you're interested in reading the discussions, they may help enlighten you as to the specific uses, value and reach of these topics. I personally have been integrating these with my SEO techniques with some success, but I'm looking forward to seeing what comes of the debate. The 3 threads are:

• C-Index - On the value of the C-Index formula
• Fractal Summarization Algorithm - On the use of applying fractals to web search and SEO
• Keyword Competitiveness - An examination of EF Ratios as applied to measuring keyword difficulty