The post about electronic maps got me thinking ...
Last January I was in Regensburg, Germany, walking through the old city. My smartphone does not receive data in Europe ($$$), but I can store a map and use the internal GPS. I also brought my Garmin GPSMAP 60csx and used that.
The buildings in old Regensburg aren't super tall, but I had a terrible time getting the phone and trail GPS's to lock onto satellites. At some point we simply did not know which direction was which, and we were struggling matching map street names with names at our location. Luckily the person I was with had a smartphone that would connect to the phone system, and that quickly pointed the right way.
Later I installed an electronic compass app on my Android phone, but I couldn't find a way to calibrate it. I never really felt comfortable that it was accurate.
So, as soon as I got home I purchased a Brunton TruArc 3 global compass to be able to carry with me in the future. It is small and rounded so it is comfortable in the front pocket of my pants. I carried an older version of the compass at the big parks in Florida and they worked great when I got directionally confused.
Like I said, I have several similar older Brunton compasses - used them to teach Scouts - and thought I had to get the newer global version for use in Europe, but later read that the need for global compasses has more to do with going north-south than going east-west, so it turns out that a compass that works in the US would work just fine in Europe. Oh well, I'm happy to support a great American-made product.
Magnetic-dip-and-zone-balancing