Google Analytics
Introducing Google Analytics. Sophisticated. Easy. Free.
Google Analytics tells you everything you want to know about how your visitors found you and how they interact with your site. You’ll be able to focus your marketing resources on campaigns and initiatives that deliver ROI, and improve your site to convert more visitors.
I’m using this service and it’s great, there really is more information than I can digest right now. All my clients will be fitted with this fab software!