If you prefer to not be tied to your computer keyboard while giving an MDID or PowerPoint presentation, then it may be worth buying a presentation remote. There are a wide variety of remotes out there, but my favorite is made by Kensington. It is available on Amazon for under $40. It has buttons for forward, reverse, and blanking the screen, plus it has a laser pointer. A newer version also has 1gb of memory on the receiver so that it can double as a USB drive. It costs around $50.