Ignoring AWS, there are lots of complex systems you can build on top of Amazon. One example is Fulfillment by Amazon. You can integrate this service with your ecommerce website, and Amazon can warehouse your inventory in its facilities nationwide, charging you based on the volume of your inventory. They will automatically select a warehouse closest to your clients that has your item in stock and pack and ship it, and even order more inventory from your supplier when a certain warehouse inventory level falls below a certain threshold. It is basically S3 backed CloudFront for physical goods.