Search Engine Ranking Factors
There are a lot of sites describing how you could improve your Google Pagerank. They usually don't add any real new information besides "Make sure you are being linked to", "Use proper META-tags", "Make sure all interesting keywords are used in your TITLE-tags and in the BODY of your documents". But here's a site that finally describes the real keytopics in Search Engine Optimization and how these factors are used to determine your PageRank.
Search Engine Ranking Factors V2
BTW: I personally think Windows Live Search crawls and indexes my sites a lot faster and much more complete then Google does but still I've noticed that Google just is used a lot more often. Let's hope that changes soon. :)