I try to work on my map-reading and compass guidance skills.
I was curious if anyone used larger-than-phone screens for maps, eg, USGS quads. An iPhone 4 is laughably small for this sort of thing.
I have a few useful things on my phone:
1. everyone's favorite, The Photographers' Ephemeris .
2. the night sky equivalent of TPE, Sky Safari . This is a great program for learning as well as planning. I have the least expensive version, it gives you all the stars you are likely to need unless you are in the middle of the desert with a 24" Dob
3. a bunch of Notes for:
a. no-parallax ("nodal") points for various lenses and cameras
b. best no-coma, sharp corners f/ stops for various lenses used on full frame camera in astrophotography, plus the faster ok-for-APS-C f/ stops if pertinent, plus declination for pertinent locations (well, one location so far, St. Louis MO)
c. soon to come, the true number of stops reduction of my brand new Big Stopper, and shutter speed conversion table
4. Audubon birds of eastern North America field guide (has songs and calls too)
5. EOS remote utility provided by Canon for its Wifi-enabled cameras (6D in my case). I haven't fiddled with this yet.
6. PhotoPills calculator and ephemeris. I got this recently and haven't fiddled with this much yet either. Hyperfocal tables, exposure equivalents, field of view, etc, plus a feature that gives you simulation of light direction at different times of day on a phone photo.
I also have a "Spot" emergency beacon that uses a satellite, pertinent in more remote areas without cell coverage (lots of the hilly Ozarks).