Virtual Cable is a solution to the often finicky turn-by-turn directions provided by some GPS devices. Rather than using a fancy dashboard module and custom map software, Virtual Cable embeds the navigation directions directly into the windshield in a surprisingly simple and potentially quite effective way.
A red line is projected onto the windshield that can accurately gauge where you are at, in relation to the drive directions. The line will show a significant right angle, curve or whatnot depending on the upcoming direction of the road or navigation directions. This could be a heck of a lot easier than trying to make out the verbal instructions from a dashboard GPS module while continually looking away from the road to see if the map looks right.
Oh and before you ask, Virtual Cable uses "unique volumetric display to create this 3D image." In laymen terms, think of it like the illegitimate child of a laser pointer, a projector and a heads-up display. [Virtual Cable via OhGizmo!]