Google Analytics is a free service that offers users up to 5 million pageviews a month. If your site generates more than 5 million pageviews per month, you will need to link it to an active AdWords account in order to avoid interruption of your Google Analytics service. Google Analytics currently defines an active AdWords account as an AdWords account that has at least one active and running Campaign, with a minimum budget of $1 per day (or the equivalent amount in a non-U.S. currency).
It seems to have passed without huge fanfare, but on April 20th 2006, the Alexa rankings for tech sites around the globe suddenly doubled, literally overnight.
Website Optimizer, Google’s free website testing and optimization tool, allows you to increase the value of your existing websites and traffic without spending a cent. Using Website Optimizer to test and optimize site content and design, you can quickly
piwik is an open source (GPL license) web analytics software. It gives interesting reports on your website visitors, your popular pages, the search engines keywords they used, the language they speak… and so much more.