Google Analytics allows you to collect pretty robust data about how users move through your e-commerce site. Here's how to make it work with Zen Cart, an open source shopping cart.

You'll need to already have a Google Analytics account set up for the application, a Zen Cart instance installed and have at least a passing knowledge with using PHP and MySQL. There's two steps to the process - a creation of a custom functions file (code provided) and a modification to two other files (the checkout success page and global footer) to send additional information to the Analytics service.