We've referenced this 189 slide masterpiece by Ask Bjorn Hansen before, but it was hidden without its own first class link. He describes his presentation as 3 hours of 5 minute lightening talks and that sounds about right.
The presentation covers: overall platform and architecture considerations involved in tuning applications from a holistic perspective. You’ll be shown design scalable architectures for dynamic, high-volume web sites. Topics covered include caching, scalable database design, replication architecture, load-balancing, and architectural decisions derived from many years of experience.
His prime directive of scaling: Think Horizontally at every point in your architecture, not just at the web tier.
You may not agree with everything, but there's a lot of useful advice. Here's a summary of some of what is covered:
This is just a high level blitz through the presentation. Topics are given a lot more detail in the presentation. Audio of Ask's dulcet tones would be nice, but there's still a lot to learn here.