Lots of site ranking services on the internet, but they are not as clear as this one: Quarkbase. Quarkbase can analyze any websites in an extreme detail. If you want to put your ads to certain websites, type the URL in the home page. Quarkbase will analyze with few seconds, and tells you everything you want to know. It includes site ranking, popularity on social websites, related discussions and more. No need to pay or request site owner for detailed information anymore.
[via ixibo]
You should also consider http://www.estimix.com They provide a nice summary of the website performance. I trust that you’ll find this very useful cause it seems to use the Alexa traffic information quite well and provides much better traffic information.