Of all the tools and web services I have ever used to find information about a website, none have succeeded in providing the most up-to-date and relevant data except QuarkBase.
QuarkBase is a free online tool to find complete information about a website.
QuarkBase gets all its data from over 30 data sources and uses many algorithms gathering information from Internet on various topics like social popularity, traffic, associated people, etc.
The information is categorized into various tabs such as traffic, people, spotlight, technical information etc. Moreover it also gives information about the inbound links, number of social bookmarks, server specifications, feed subscribers and traffic sources.
The information is very relevant, 99% accurate and well organized. You should definitely give it a try.