A friend of mine just bought two new machines, and is building a web garden. He wants to grow it into a full fledged web farm. Of course, cart before the horse, he doesn't know what he wants to do with all this processing power, but he wants it. This is a person who read a 1200 page book on VB Script before writing his first dim statement, so that's just how it is.

Still, knowing that I'm the "web guy" (outside of tech, people peg you as a computer person - in a different corner of tech, they peg you as knowing the web), it's up to me to give advice. Anybody have any I can pass along? I've mostly just wrote backend code usually data access stuff, so I don't know anything about using 8 servers for 1 site.

All about server farms, in just the one post?

Two ways basically;
Clustering (using software) and Hardware, or a combination depending on how resilient the network has to be.

Failover Clustering is mainly about availability, and is where the machines operate in a redundant capacity, so should something fail the next in line takes over.

Load Balancing (This is the more common server farm mode) is where a device handles the incoming requests and passes the tasks on to parallel computers (or clustered groups)

There are also High Performance Clusters which is the kind of thing that Google runs on, where the software is specially developed to run tasks in parallel on individual processing nodes.

Using a HPC does not mean that everything will run quicker BTW (in much the same way that a dual core CPU doesn't mean Windows will run any quicker ) (Anybody remember the INMOS Transputer? )