Storm

http://www.alexa.com/company/technology Their toolbar is a new feature they have it helps to rank a website but is not required. They crawl the internet and gain statistics ect... that's why they are not always correct.

I have to say you are completely wrong about the Alexa ranking What alexa does is calculates how popular a website it and where your visitors come from and then they rank your website you do not have to and never had to download the alexa toolbar or your users have to download it for your website ranking to go up it is all automatic and people if popular and successful websites should know that.