Over the last few months I've been playing a lot with my Nokia 6680. My favourite software add-on to it is the excellent TomTom Mobile.

I was lucky enough to borrow a friends copy when they had to go and work in the US.  Sadly, for him, TomTom Mobile does not have US maps. Good for me though!

To provide GPS data I use a Fortuna Clip-on GPS receiver. This chats with the phone using Bluetooth so less cabling needed. The Fortuna is useful in that it has an socket for an external antenna so I installed mine in the glovebox and put an antenna on the dashboard. This makes the car look a lot neater.