I used to use Urchin for all my sites and client sites (Server side analytics), but Google bought them and it is no more. However, I believe a lot of the Urchin technology has been filtering through to Google Analytics.
I don't use it, so I don't know if its that good, but Mark has used it for ages and raves about it. So he would be a better person to tell ye about it. The thing thats putting me off using it, is on WebHostingTalk, their have been a few threads questioning the reliability and accurateness of the service???