Alexa

Founded in April 1996, Alexa Internet grew out of a vision of Web navigation that is intelligent and constantly improving with the participation of its users. Along the way Alexa has developed an installed base of millions of toolbars, one of the largest Web crawls and an infrastructure to process and serve massive amounts of data. For users of Alexa's Toolbar and web site this has resulted in products that have revolutionized Web navigation and intelligence. For developers this has resulted in a set of tools unprecedented in scope allowing whole new services to be created on the Alexa data and platform. (Source: Alexa )