E-commerce is an antiquated term at this point: e-commerce is commerce. While it has long been common for an established brand or merchant to supplement their primary "High Street" retail outlets with an online shop, extending access of their trusted products to their loyal customers online, the core business model has always been built on the in-person shopping experience that "brick-and-mortar" locations provide. There is no substitute for the personally-familiar: assessing the quality, fit, and finish of a product as it rests in one's hands cannot be replicated, and it is that upon which so many established retailers have based the value of their online shopping experience, to great and earned worth.
There have obviously been a number of challengers to this model over the years. Many have failed (Pets.com is a famous example), but several upstarts have found a unique niche and have thrived.
Whether an extension of a traditional shop, or a web-only experience, to be noticed in a crowded field it helps to have a good looking site. Here are 9 of the best designed ecommerce sites around, IMHO.