There are a few sneaky tricks you can do in PowerPoint if you have multiple monitors running.
First, you can have notes showing on one monitor and the slides showing on another. This is especially helpful if you are running a presentation. Turn the screen towards you and show the PowerPoint notes interface on it. Then, project the running program on the screen for the participants to see.
Next, if using PowerPoint for a meeting where you need to preselect or change content while the show is running, you can be working away at the slides without the participants knowing. If you do this, the changes won't show until the slide is re-started on the screen. So if editing the slide being shown, the changes won't show until you leave and re-enter the slide.
Finally, you can have two presentations running, one on each monitor. They will not actually run at the same time, but they will both be visible at the same time. (In other words, only one presentation will be active and animated, but the other one will be visible.)