Luckily it’s 2009 and there have been a bunch of successful websites that have had to deal with large scalability challenges. Many have been kind enough to share their knowledge with the world. Here is a list of the best books, articles, presentations and practices from the likes of Twitter, Facebook, Flickr and more.
Cal of Flickr fame has written the definitive resource on scaling web apps.
Another great resource, focused heavily on the MySQL portion of LAMP, which is the hardest part to scale.
Scaling Twitter in Ruby (slightly dated)
Twitter was originally architected in Ruby on Rails and had some pretty serious scalability issues resulting in the now (in)famous fail whale. His presentation is insightful and the basis of many of their inital scalability measures (now failing as twitter has reached a magnitude larger than when this was given). Presentation given by Blaine Cook.
OSCON has been a major source for scalability presentations. In 2006 Rasmus delivered this presentation. Rasmus is notable for being the creator of the PHP programming language. Niall Kennedy recorded the audio and provided it as an mp3 here.
Scaling Web Apps
Cal, the author of the first book mentioned also put many of the same principles into a talk given at WebExpo 2007.
The same talk given (and updated) about a year later.
LiveJournal was the first open source LAMP based Web 2.0 company to hit massive scale problems. They developed many of the strategies and tools, including memcache, that flickr.com, digg.com and facebook.com are using today.
Brad Fitzpatrick gave a good presentation about how they grew, both the challenges they faced, and the solutions they came to.