My hunch is the answer is: "it depends". How do you measure the growth of your site? Is it based on page views, subscribed paying customers, registered customers, ad clicks? I know the obvious question may be revenue growth, but what about before the revenue starts to roll in? What metric is the most important for a certain situation?
I'd love to hear a whole spectrum of thoughts.
I use Google Analytics for site stats, it's pretty informative once you understand where everything is.