Use more than one master in a presentation
You can use multiple masters in a presentation if you have PowerPoint 2002 (XP) or higher. And amazingly, presentations with multiple masters will play back correctly in PowerPoint 97 and 2000, though you can't edit the templates/multiple masters.
If you want to give the appearance of multiple masters in PowerPoint 2000 and earlier, you have to think slightly outside the PowerPoint box - and outside the presentation itself. Think: LINK.
Have a look at the small sample presentations in PRESDEMO.ZIP to see how all this works together.
The key points to remember are:
Set the presentation to run in KIOSK mode
Use action buttons or graphics that you draw/import to control the action. Draw/import navigation icons and assign suitable hyperlink actions to them to let the viewer control the show.
Tip: If a particular navigation icon will appear on every slide in the presentation, put it on the Slide Master. That way it'll automatically appear on every slide.
For more ideas, visit PowerPoint MVP Echo Swinford's site, Echo's Voice.