Alk Technologies has produced a free version of its offline navagation app Copilot Live, called
CoPilot GPS.
2D display only and no voice prompts, but would be good for the casual user for those times when there's no WiFi for Google maps or for those who just want to try it out. Maps are downloaded from within the app and stored on your device, so you do need to plan ahead and download the proper regions
before you get lost
. These are street maps only, so no help if you get lost in the woods, but may help if you get lost in an unfamilar city and pigeons keep eating your trail of breadcrumbs...