Something—I'm honestly not sure what—has changed in Mac OS X Leopard in a subtle way that has totally derailed my workflow for making presentations involving code samples.

I give a lot of Keynote talks that are very heavy on code samples. For years, I've had a workflow for creating code-sample slides that's worked pretty well for me:

First, I create a directory for the slide show. Inside is my Keynote presentation, and subdirectories for ancillary materials. The relevant ones here are code-samples/ and images/.

In the code-samples/ directory, I create little files containing the code fragments. I edit them in Aquamacs Emacs (a very nice Aqua GUI for GNU Emacs) which gives me code syntax highlighting: