There’s an interesting list of Google Ranking factors I’ve had bookmarked for a while which lists quite a few considerations on how Google (may or may not) rank web pages. Some of the info comes from observations and experience and some comes from a review of Google patents.
I noticed a post on Rand Fishkin’s SEOmoz site today where he lists an excellent article on overall Search Engine Ranking Factors. As usual, Rand’s work is exceptionally well done and professional. Danny doesn’t necessarily agree with all of them, and that’s fine. SEO is a moving target and search engines want to keep it that way.
Regardless of the details of particular search engine ranking factors, the three things that I have found to always be true in regard to rankings, at least since Google has been around, are: indexing, content and links. Here’s a previous post on better rankings that elaborates on that concept.