Statbrain is a online web stats tools that helps you guess the number of page views on any site using a combination of Alexa rank, backlink counts from Google, Yahoo and some other unknown factors.
Don’t expect it to be too accurate, but if you want a very rough estimate for any site, this could be useful.
This could be very handy for advertisers or people who are interested in measuring rough traffic on a competitor’s website.
You may also want to checkout Google Trends as they are pretty accurate.
StatBrain gives an estimate about number of visits and not unique visitors or page views. If that sounds confusing, let me explain: