It seems like tons of great applications utilize PHP for scripting and MySQL for data storage. Perhaps you could do some technical discussion of each, with emphasis on how they can be effectively coupled together. I think that this would help a lot of us better understand the systems that are commonly in use on the web today (i.e. Drupal, Wordpress, etc.). As I suggested with the Javascript libraries, this might be something better suited for a screencast or videocast if it's too difficult to cover with just audio.

This is a topic that I have always wanted to learn more about but seldom had the time to do so. I think that lots of people could benefit from some technical discussion of what javascript libraries are, but more importantly how to implement them. If this is something that is difficult to discuss with audio alone, maybe a screencast would be better. I especially think that it would be useful to discuss how to use jQuery within Drupal since it is included in core now. I know that it can do some pretty cool things, but I have no idea where to start with implementing it on my church's Drupal site.