Google Analytics is one of the best ways of tracking the activity on your website. Using Google Analytics you can have a regular (daily/weekly/monthly) report generated to show you everything about how your website is performing, from how many visitors you have had to what pages they looked at, how they got to your site and, if they came via a search engine, what words they used to search to find your website. These Google analytics reports can be set up to be automatically emailed to you so that keeping tabs on your websites activity can be done in 30 seconds.
Google Analytics are an absolute necessity if you are testing and measuring your website to determine if and how it is growing.