Google Analytics offers statistics on usage of your website. Wagn makes it easy to take advantage of this.
To get a Google Analytics key (which you'll need to use this), learn more about it, or see the statistics for your Wagn once you have this feature set up, see http://www.google.com/analytics/
Create a *Google Analytics Key card on your Wagn, set its cardtype to PlainText, and enter your Google Analytics Key. Your Wagn will use that key on every wagn page (except those with "none" as a layout - see web address for everything).