PNF Duo Digital Pen Mouse

The PNF Duo Pen is an interesting device that brings some touchscreen tablet functionality to standard laptops. You attach the USB receiver onto your laptop's screen in a similar way to a webcam, which responds to the movements of the pen itself.

Instead of a clip for the receiver, however, you tape a small magnet onto the back of the screen, which allows the receiver to be attached quickly and firmly. Although this solution works, a clip would have been much more preferable. The outer shell of your laptop is left with an unsightly magnet attached to it this way, and it means you can't easily use one receiver with different laptops.

Once you get past that rather odd design decision, the PNF Duo Pen works well. The receiver tracks the motion of the battery-powered pen decently, although you have to calibrate the screen using the included software first.