On the Webdigity.com forums, there's this new tutorial posted showing how to create a simple caching system with PHP for your site (using cached files).

A problem that this process creates is the server overhead. Every time we execute a query in the database, the instance of our script will call the DBMS, and then the DBMS will send the results of the query. This is time consuming, and especially for sites with heavy traffic is a real big problem.

There are two ways to solve this if you want to make your site faster. First is optimizing the queries Visit through proxy, but we will not talk about this at the present article. The second and most valuable is using some kind of custom caching technique.

Their code, contained in an easy-to-use class, makes it simple to cache the contents of a page just by setting the stop to start the caching from (and where to end).