Although various GPS units already have the ability to display the current speed limit (they're pre-programmed in) of the road you're on, this Vauxhall Motors invention seems even better. There's a camera on-board that takes 30 snaps per second, then recognising speed limit signs and translating that to a number to display on your dash.
This way you can know exactly what the speed limit is at all times, even when you've just transitioned from a high speed area to a low speed one that cops like to ticket in. In fact, if this system is good enough, it could be a decent excuse to tell the popos that their speed limit signs were too obscured that even a 30FPS camera couldn't make it out. [Kicking Tires via Oh Gizmo]