Simple-PHP-Cache is a project mainly written in ..., it's free.
A simple class to allow data caching to files
Caching data, especially SQL queries is one of the most important aspects to writing fast php applications.
The problem I had was that the existing caching engines around tend to be very powerful and feature rich but at the expense of a fair bit of overhead.
So I wrote this short class. It's simply a very basic file cache. It can write cache files, retrieve them and delete them and that's all.