Interactive map

[NZ_Kiwis]

I'm designing a project now which will have cities saved into a DB. Say Auckland, Sydney, London (I would add more details than just a city name to the DB). But what I want to happen is when a user loads a page there is a line between city pairs ie: Auckland and Sydney come up there would be a line between these...

Problems I have is there are a lot of cities in the world, would I have to add each one to the DB or could I use something like google maps and when a user adds say Sydney into a web form it finds sydney somehow....

am I making any sense???

Ideas/thoughts?

[NZ_Kiwis]

I guess I want it to look like this Click here (http://erequest.airnz.co.nz/booking_support/maps/book/mapreceive_en_NZ.htm?a0=-37.009999933359204|0101||AKL||2007,9,12,7,0,0||3h30|||174.7913887029673&a1=-33.946666643155815|0101|SYD||2007,9,12,7,30,0||||||151.17666652209255)

but a user will add almost any city pair in the world.

[scrupul0us]

google has this documented fairly well in there API documentation