Using AWS to Build a Graph-based Product Recommendation System by Andre Fatala and Renato Pedigoni.
From the description:
Magazine Luiza, one of the largest retail chains in Brazil, developed an in-house product recommendation system, built on top of a large knowledge Graph. AWS resources like Amazon EC2, Amazon SQS, Amazon ElastiCache and others made it possible for them to scale from a very small dataset to a huge Cassandra cluster. By improving their big data processing algorithms on their in-house solution built on AWS, they improved their conversion rates on revenue by more than 25 percent compared to market solutions they had used in the past.
Not a lot of technical details but a good success story to repeat if you are pushing graph-based services.
I first saw this in a tweet by Marko A. Rodriguez.