The current version of Google Analytics has been greatly improved since the buyout of Urchin a few years ago.  This web analytics package now has the capability of relating most any action on a website to dollars.  An e-commerce website can be linked to your internal search engine to see which search terms people use that produce the most revenue.  Your e-commerce site can also be linked to your landing pages bring in the most revenue.  Google Analytics also allows for adding up to 4 specific website goals.  Here you specify the paths you think customers will take to result in a conversion.   In an e-commerce site an obvious goal is to track what happens after a customer adds a product to their shopping cart.  Once a product is added, that customer should complete their order.  If an order does not complete, your Google Analytics goal will help you to figure out what went wrong by showing where most customers leave their carts behind.