Amazon's 2010 shareholder letter
Jeff Bezos' 2010 letter to Amazon shareholders goes in-depth on their technology, covering service oriented architectures, state management, topic modeling, object caching, etc.
All the effort we put into technology might not matter that much if we kept technology off to the side in some sort of R&D department, but we don't take that approach. Technology infuses all of our teams, all of our processes, our decision-making, and our approach to innovation in each of our businesses. It is deeply integrated into everything we do.
It's worth reading in full. There's nothing in here that should be a surprise to anyone that's paid attention to Amazon's technology over the years, but the letter signals the depth of commitment that Amazon has to ongoing R&D. It's a reminder from Bezos to Wall Street: "Hey, you know what's been driving our growth over the last five years? This stuff. And we're not letting up."