A neat new WebmasterWorld thread is trying to do the impossible by putting down on paper, what exactly are the 200 or so search engine ranking factors used by Google.
The thread creator put out a few dozen ranking factors, but there is a way to go here. Think this is a possible task?
Even if they do get all the 200 ranking factors down, figuring out the weights assigned to each and how Google scores them based on other factors can be a bit complex. SEOs have been trying to do so since even before Google was born. Back then, it was a lot easier, now - it is virtually impossible. I bet Matt Cutts, who has access to this data, wouldn't be able to get it exact (no offense).
Anyway, trying to come up with the list, in itself, is useful on some level. But understanding where to put your emphasis and time in, is what is most important for SEOs to understand.
Forum discussion at WebmasterWorld.