Action Settings provide a means of providing some interactivity through telling Powerpoint to do a specific task, such as open a website. An Action Button is a preconfigured graphic which is packaged with a choice of Action Settings. Action Buttons include clickable forward/backward navigation, a help button, and even a customizable button. Action Settings can be added to most any graphic or sound by using the Right Click properties menu.
Let's add some linking buttons between sides.

Main Menu > Slide Show
Action Buttons> Choose
As you can see there are a lot of choices including:
Examples: Using one Powerpoint presentation for a menu structure (only navigational elements)and then mini presentations linked from there, see the Cataloging Tutorial, http://www.libs.uga.edu/catalog/tutorial/
NOTE: To place an Action Button on every slide, you could add it to the Master Slide. If you only want it to appear on some slides, copy and paste.
Choose Hyperlink to Next Slide.
Click OK.