Tracking user activity is the main way to measure this, your file server may provide log file access so you can determine the number of unique visitors a day, or you can install tracking software like the very comprehensive Google Analytics or the easier to use Statcounter.com
There are sites that rate the popular of larger sites, like Alexa.com. new sites will not be in their system.
Google page rank gives an overall rating of each separate page, based mainly on the number of sites linking to it, a browser plugin or certain reporting sites can give PR.
you can check through visitors of website, bounce rate and tracking user locations.
You can check with Google webmaster and Google Analytics.
You can check alexa rank then u will come to know the popular or not...
you cheack google webmaster tool
see alexa - this is good indicator
