ShowPointer is a fine alternative to the traditional laserpointer if the event features several presentation screens running in parallel. With ShowPointer the speaker can easily highlight areas at slides in a way that can be watched on all screens.
ShowPointer is operated from a touch screen displaying the signal from the PowerPoint presentation. Touching the screen will show a standard laserpointer dot on top of the presentation but as an extra advantage movement are tracked and will stay on screen for a short while if the presenter wants to circle a section on the slide thus carrying the interaction to all displays at the conference.
There is more info at the Touchpointer site which features the commercial version of the product that includes all necessary equipment for a professional conference setup.