I like the knightrider sample idea a lot

But gpsapp really isn't running when it is not in the foreground. It would need a separate thread that would keep polling the serial port while the main thread is waiting in the hijack menu.

The audio device is probably not shareable as is without something like Kim Salo's audio overlay hack in hijack, but we need hijack already so we just need to brush up the patch and see whether Mark wouldn't mind adding it. It is probably best to make sure we get it to work before that.

My guess is that playing a tone is about as difficult as playing wav's and with wav's we could even have something like 'left turn coming up in 2 miles'.

An even better solution might be to use a set of prerecorded wavs for turn/distance information and combine those with festival/flite generated streetnames. Ohh, the possibilities.