Amazon.com continually raises the bar for online retailers.
That success is no accident. Every change made to the site is tested, every move researched through focus groups, user testing, and strategic analysis--all of which is great news for you, the online retailer; it's like having a million dollar consultant by your side as you grow.
For example, when Amazon partnered with CDNow, they revamped CDNow's look and feel so that it mirrored Amazon.com's to a T. The CDNow look was scrapped altogether; stop by their sites, Amazon.com & CDNow.com, you'll see. The two site designs are so identical that it seems like CDNow is one step away from renaming the site CDamazon.com!
Why Did Amazon Completely Scrap the CDNow Design?
Amazon knows that their site is designed in a way that works, and works as well or better than any other online retailer.
How do they know it works? They test and analyze the impact of even the smallest changes. They even have dedicated user experience and web metrics teams. Your company may not have the ability to have entire teams dedicated to these important site functions, but the result of Amazon's hard work, at optimizing user experience and analyzing what works, is culminated in the design of their site, for all to see.
While I don't recommend you create an Amazon/CDNow version of your site, I do recommend that you stay aware of what Amazon is doing--some of the changes made to their site may be useful for yours.
Leverage Amazon's R&D for Your Site