Attach a knob to your display
Here's their description:
"SenseSurface can be used with most laptops with a USB input. The sensing knobs have a custom designed movement sensor to determine position within a range of 180 degrees with a 10 bit digital output, linearity typically 1%. The magnetic knobs can be removed and repositioned immediately by picking them up and moving to a different part of screen. A unique sensing x/y matrix is attached to the rear of the laptop screen to detect the control's position. The distance of the sensor from the screen can also be detected. The rotary controls are low friction and there are no screen finger prints as with normal touch surfaces. Linear sliders and switches can also be used on the lcd surface. For audio use, a logarithmic response can be programmed. The system is multitouch and scaleable , the number of controls on the screen is limited by the size of the screen. The screen can be at any angle."
Why do I blog this? I find intriguing the notion of gestural interface through knobs as a an add-on to a normal input/output device.