A place to start for each Amazon Web Services projects:
http://aws.amazon.com/architecture/
Interesting eCommerce architectures:
1) AWS_ac_ra_ecommerce_webfrontend_14
2) AWS_ac_ra_ecommerce_checkout_13
3) AWS_ac_ra_ecommerce_marketing_15
You can find more info about this topic on Amazon Web Service site:
https://aws.amazon.com/blogs/aws/three-new-aws-reference-architectures-for-e-commerce/