I always go back to these presentations at least once a year to review performance and scalability.
Amazon and eBay are architectures that makes any developer salivate or wonder, "how they do it?". The Werner Vogels and Randy Shoup are (at least to this humble developer) awesome architects which we can learn MUCH about what they do best; architect high available, high performance, and highly available architectures. Werner Vogels discusses the CAP theorem very well, and how it's a KILLER to current applications. Shoup discusses the forces that take place when you develop these type of architectures.