You guys are welcome. I'm glad to see a site where someone is at least trying to take a scientific approach to SEO as opposed to the general and unsupported comments often found in forums.

For my own efforts (I'm not an SEO, just a guy with a little ecommerce site), I made up the following formula. It's only a simple model to guide my efforts - nobody really knows what the Google algo is or how much weight they assign to each factor.

SE Position = (On Page Relevance X Link Popularity X Site Quality Factors)

Negative On-Page Relevance: Keyword overuse or underuse, hidden text, duplicate content.
Positive On-Page Relevance: Words and phrases supporting your keywords. Natural text structure. 150-350 words, 3-5% keyword density. Use of related words.

Negative Link Popularity: Number of links from link farms, "graybar" sites, and sites unrelated to your theme. Using link schemes.
Positive Link Popularity: Number of links from high PR sites, authority sites with your theme, and links with anchor text = your keywords and variations of your keywords.

Negative Site Quality Factors: Doorway pages. Unable to spider site (frames, Flash, etc). High code-to-text ratio. Banned IP block. Porno language. Dynamic pages.
Positive Site Quality Factors: Age of site. Age of inbound links. Valid HTML. Number of pages. Outbound links to authority sites.

It's just a very general model I use. Feel free to throw rocks or add to it.

Ed