I don't know about on a curve if they have an app..
I use a Tom Tom one XL/s in my car. I had a GO 300 till it got stolen.
In my car I use the tom tom traffic service, but I am about to drop it because I get the same info off 1010 wins or news radio 88...
I use a Garmin when I am out of the car. I got the 8310 for GPS but Ill be dammed if I pay for the nav service. I should have checked in a little more because I would have got Wifii BB instead..
I will DL Google for the H%LL of it when I do not need precise GPS and start looking at the other apps out there.