Signpost

We have all seen those signposts - the ones stuck in the middle of nowhere with a multitude of signs pointing to famous places (London, New York, Yoko, Rowville, etc). They all point across the surface of the earth - presumably to follow a great circle to the desired locale.

I want one which points as the laser shoots. THROUGH THE EARTH! Especially from Australia, this would be pretty neat I think, with most of North America and Europe being various points DOWN. (in fact, north america and europe are the most 'down' you can get from an australian perspective. More interesting stuff would be in the directions of africa, Asia, south america, antarctica, NZ...

For bonus points, instead of a signpost, make it out of actual lasers! (and sealed in a cage with appropriate gas so the line of the laser is visible. Say, ALL lasers always visible in red, then you select a city and it goes GREEN!)