Scott MacVicar shares a helpful hint for the PHP speakers out there - how to apply syntax highlighting to the code in your slides.

I use Apple's Keynote for doing my presentations and naturally these include some bits of code that need highlighting so that it’s easier to read. [...] In the end I used GESHI which is a highlight library written in PHP that supports the syntax highlighting of around 50 different programming and scripting languages.

He's provided his sample implementation to help you get up and running. You'll need to download and install GESHI to get it working though. Here's an example of the output.