Sales-n-Stats now have a free version targeted for small and medium sized e-commerce sites. Good addition for growing e-commerce business.

Quick quote from Sales-n-Stats site:
Personalized visitor tracking.
Live Chat feature is backed up with background information about a visitor.
Real time data processing: No lags or delays. All data are live.
A unique system of live visualization of the site visitors (Site Monitor)
Ability to create custom reports in minutes.
VoIP feature to talk to your web site visitors.
You own the software and statistical data and do not have to share it with any third party.