Hi Shari - we don't have a navigaton app I'm afraid and don't have any specific recommodations for ones that include voice instructions. CoRider had voice navigation but I'm not sure it still exists. I'll see if we can put together a list of recommendations at some point.
Is there voice navigation for my iPhone? Will it let me know either by stating exact streets and where to turn or by a "ping" letting me know a turn is coming up?