On ibzi's blog today, there's a quick guide to introducing caching to your PHP application via a simple PHP file to create the cached pages.

Caching your pages can be pretty useful, especially if you have PHP-generated pages that uses a lot of MySQL queries. Once your pages are cached, your server won’t waste speed and RAM on regenerating the pages, it will just load it from the cache. I’m going to show you how to get PHP to cache your pages, and you can probably do this within 5 minutes.

You'll need to be able to add (and use) an .htaccess file for Apache to use this method, but once it's set up, the simple script works like a charm. It prepends the caching functionality to each page and checks to see if a copy already exists. If it does, it displays it and if not, it will display it and create the cached file.