in reply to
(OT) Presentations Involving Code
You might want to find out whether the machine in the lecture room will have internet access, and if so, perhaps it wouldn't be too ambitious to set up some sort of demo web site that will display some canned perl script(s) with instructive inputs and outputs. I guess if you're lecturing about a module that provides a wrapper for a commercial web-based API, having internet access would be really nice.
In the absence of that, I'm not sure where to go -- grab some screen shots and just present those as images?