Follow up to my previous post on effective presentations. Lately I have been using this neat little program called AIRMOUSE which runs on any iPhone 3G or 3GS. You can go to their website to download the Mac and PC companion application.

Once you installed, you can control your Mac or WindowsPC using your iPhone, using the WiFi built in to both the devices. Due to the range of the WiFi, which is typically 100 metre, you can literally control your PC or Mac powerpoint, mouse or even your iTunes/WindowsMedia Player from behind the room.
That is a pretty cool thing to do.

For more information: check it out at http://www.mobileairmouse.com/