Most of the designers who build sites with the Webvanta web content management system use Google Analytics. It's simple to add, it's free, and it's pretty darn good.
It does have some drawbacks, however:
Webvanta now includes built-in analytics for all paid sites. Within a day of when your site goes public, you'll see a new tab show up in your control panel, labeled, curiously enough, Analytics. And that's what you'll find there. No setup required.
It will even tell you who is visiting your site, right now, and how they go there. Of course, we don't know who they really are, but you can see their IP address, and where they are (approximately, since IP mapping is inexact), and if they've been to your site before. You can also see a list of the 100 most recent visitors.