I wanted something that was more real-time than Google analytics to help me track traffic to all of the websites that I am the webmaster for. Google Analytics is not bad, but I hated that you have to wait until the next day to see the traffic for the previous day. After searching for something else that would show me real-time traffic, I found goingup! and I must say I am very impressed.
One of the things I like best about it, is that it shows the alexa rank as well as the google page rank for your site. It also shows you how many inbound links your site(s) have from Google, Yahoo,MSN and Alexa. It also shows you how many pages from your site(s) are index on these same search engines. It also shows you what key words were used to find you if the traffic comes from a search engine. Another good feature is that it shows you the referring page that your traffic came from which helps to show you who is linking to your website.
I highly recommend goingup!