Leon Chevalier has posted about a class he's developed (you can download it here) that can help to speed up the load times for your site.

There are 4 relatively easy ways by which you can speed up the time it takes a browser to download a page. Following on from my post on joining CSS and JavaScript files, I have written a PHP script which will automatically do all of the above.

He gives example code of the class in action and includes some screenshots of the benchmarks from the YSlow Firefox extension showing the improvements.