Are there any good offline maps apps for Europe and North America?

For what sort of device/operating system? TomTom (iPhone) and CoPilot (Android) are good for smartphones.

For Android you can download "Mapdroyd" from Market for free. It is not as nice as Google maps but allows you to download entire countries in advance for use with no data service.

For the more adventurous Android user there is an unauthorized hacked version of Google maps that has map caching for offline use as well as enabling Navigation in many countries that Google does not support. Unauthorized and not Google approved so it is not in Market. You can read about it and download the .apk herehttp://forum.xda-developers.com/showthread.php?t=630887

If you are not using Android, I can't help you

I recently evaluated several offline mapping tools for android, including MayDryoid.

My favorite by far is OsmAnd. I cached several cities I'll be visiting in October without a data connection.

Any suggestions for Windows Mobile?

Microsoft Streets and Trips and/or MapPoint used to have a WinMo version. They may still, I don't know. Might be worth checking into.

The nice thing was that you could build custom maps on the desktop app and then sync them over to the device.

Ones I have tried for iPad include National Geographic World Atlas and the four ScenicMag apps for the US. None are all that good. National Geographics gives you some detail for every country but needs a WiFi connection to give you really good detail (via Bing). The ScenicMap apps are good but very slow usually. I have tried tracking our progress while flying commercial and got it to work OK once but it is far from consistant and not the best UI. They need work. I also have TomTom and Navigon on my iPad but they are not all that easy to use as purely maps. I also have a Garmin nuvi and that works OK even when flying commercial but still not real user friendly as purely a map.

There is definitely a need for great off-line maps.

Any suggestion for Windows PC platform?

GMAP catcher

http://code.google.com/p/gmapcatcher/

Microsoft Streets and Trips is the Windows PC application; if you have a Windows Mobile device it will install that for free as well. I've been using MS S&T practically every day for years and have been very satisfied with it. Hotel brands get out of date, but for all other purposes it's a great tool. The European version is MS Autoroute.

Thanks for the link. Looks interesting.
On the linked page, I see 4 downloads (2 mapcatcher; 2 GMapCatcher). Do you need to download all 4 or simply GMapCatcher-0.7.5.0.exe?

For the IPhone, I use OffMaps. You can pre-download city maps and use it with conjunction with GPS. It's changed the way I travel!

Thank you all! will give it a try

This is where Ovi Maps for Nokia phones really excels.

Offline maps, turn by turn navigation, etc. For free.

Any updates on this thread? I'm running winmo 6.5, and it looks like Mapcatcher's website has Google maps crossed out now. Did they stop support for Google maps?