Alexa Certified Site Metrics is an analytics service wich monitors and analyses web traffic and can be used to keep track of user behavior.
Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
DoubleClick Ad Exchange is a real-time marketplace to buy and sell display advertising space.
Google AdSense is a program run by Google through which website publishers serve advertisements that are targeted to the site content and audience.
Google Analytics is a free web analytics service that tracks and reports website traffic.