preface: I've had my eye out for a free GPS app with offline routing for a couple months now, and as far as I can tell, there is none. So, the question is, which app do I settle for? This list should help answer that question and others. Maybe it will find its way into the wiki someday (?) in some form or another. Lots of people use their IT for GPS, so it seems like there should be a complete list of GPS apps somewhere--EDIT: GPS navigation/mapping&tracking apps, and I couldn't find one anywhere. So, here's my attempt:

1. Wayfinder (a.k.a. "Map"): pre-installed, free, vector-based mapping (entire US in less than 2 gb of map files), very stable, finger-friendly
   
2. Wayfinder with paid license*: expensive, but you get all of the above PLUS offline voice-guided navigation
   
3. Roadmap: free, vector-based mapping
   
4. Maemo Mapper: free, image-based mapping (OpenStreet, Google Maps, Yahoo Maps, or other formats; storing the entire US at every zoom level on your IT is out of the question), voice-guided navigation for routes imported from google maps (must be online to calculate routes)
   
5. Navit: free, vector-based mapping, offline point-and-click routing (typing in addresses is broken)
   
6. TangoGPS: free, image-based mapping
   
7. Hike: free, image-based mapping (using imported JPG or PNG < 12 MB)
   
8. Cumulus: free, vector-based mapping (KFLog format), specialized for flight navigation
   
9. GPS City Guide: free, image-based mapping (OpenStreet format), displays tourist POIs and links to online wikipedia info about them
   
10. zmapper: (?) currently unstable. has anyone out there tried this?

*Some have tried--and fewer have succeeded--in cracking the 7-day trial period offered for voice-guided navigation with Wayfinder. While I don't support this behavior, I feel obligated to list it as an "option" here, for the sake of completeness.

I intend to edit this list according to suggestions/corrections/updates. so, please comment/criticize.