WebmasterWorld has a great thread going about the 200+ variables (yes 200+ according to Google’s Matt Cutts at PubCon) that Google uses in their search ranking algorithm.

Some of them are well known such as age of domain, keywords in the domain, URL path, keyword density, title tags, Meta description keywords, header tag keywords, freshness of content, alt tags, inbound link quantity and quality, anchor text, and many more items that have been around for years as a part of Google’s ranking algorithm.

But there are a ton more ranking factors that are much lesser known such as IP location, location of links, use of external CSS or JS, TLD of domain, etc. listed in this thread.

I strongly suggest reading the thread and perhaps listing your own factors.  Enjoy!