Portable Side Mirror will help those of you that want to open a presentation on a projector for the audience and also have your notes in plain view at the same time.
This particular application will help you extend your desktop and not duplicate it in order to keep everything you need on your screen, including the presentation. While there are programs such as PowerPoint that automatically send the slideshow to your second monitor, they come at specific price tags - and they simply are not cheap.
NOTE: Portable Side Mirror also comes in the standalone version that you may check out here.