Google Analytics operates:
Google Analytics, Google Website Optimizer
Google Analytics is a free service offered by Google that generates detailed statistics about visitors to a Web site for marketers. Google Analytics makes it possible to track users across search engines, email campaigns and display advertising giving advertisers the opportunity to optimize campaigns on multiple platforms.
AddThis - Facebook - Google Analytics - Google Custom Search - Histats - Omnituire - Scorecard - Sitemeter - Specific Media - Turn