A few little things we've discovered over years of programming, editing and operating PowerPoint:
resizing an A4 slide
sending your non-standard font with your presentation
reducing file size by compressing pictures
getting quickly into slide-show mode
importing slides from a different presentation without changing their look
The latest version, Powerpoint 2010
getting a sound to keep playing over several slides
drawing guides
packaging a presentation to use on a different computer
the difference between .ppt and .pptx
loading up a .pptx file in an earlier version of Powerpoint
.pps and .ppsx files and how to edit them
Displaying page numbers in 2010
(overhaul in progress - sorry if some of this doesn't quite work)