GPS Software

I am looking for a nice GPS enabled mapping app. Basically I want to use my MBA as a GPS direction thingy when in the car.

So far my googling has only resulted in apps to work with in-car or handheld GPS units, not for using the MAc itself as a route finder/guide.

I have a GPS receiver (a nokia bluetooth unit) that talks to the MBA ok. I just need advice on mapping software (one that covers Europe).

Has anyone got any advice on this one?

Thanks (btw this is more fun/curiosity as I dont have to use the route finder really)