Okay, this is some pretty cool stuff! Microsoft Labs (kind of an R-&-D group that releases software that MS makes no guarantees about or support for) has made a PPT 2007 add-in that changes the way you think about slide navigation.
Imagine one slide having a dozen very very small thumbnail images of other slides and then those slides having even smaller thumbnail images of more slides. View the first slide, click on a thumbnail and zoom into it. Go through the slides in order or zoom back out to go to a different topic/section!
This one is easier to see explained, so click here for movie overview. I will be experimenting with PPTPlex this week and should have a few samples posted.
– Troy @ TLC