I am an Android phone user, and over the last year or so, I have played around with various radio related applications. I thought I might start posting some useful ones here. Unfortunately, I do not also have an iPhone, so I suppose I'd have to rely on others to see if these apps (or similar ones) are available for that platform.
Now, I know in a STHF scenario, odds are, your smart phone is going to be nothing more than a PDA, and that's IF you can get power for it. Battery life isn't great on any model, really, but just for the sake of discussion, I'll throw a few apps that I've found in this thread, and you guys can decide if there's an interest for me to keep exploring them. There are a few worth some thought that you don't need to be connected to a network for them to operate.
Also, I wasn't sure what category to put this in. So, if it's in the wrong one, let me know.
First up is an app called Signals. http://www.appbrain.com/app/signals/com.apklabs.android.signals (http://www.appbrain.com/app/signals/com.apklabs.android.signals)
This is simply a cataloged reference of codes, verbal or otherwise, used in various situations and professions. Everything from 10 codes, Q codes, Medevac all the way around to scuba diving hand signals.
Why might this come in handy? Well, I can see learning or at least having a reference of these things being good for deciphering police or rescue traffic you may be listening to, and in the event of an emergency, I don't know about anyone else, but I'd kinda like to know what they are saying, since that knowledge might help aid your own decisions about what to do. I don't know that ALL police, fire or ems obfuscate their messages with such codes anymore, but I will say many of the ones in my area do (it's actually a bit fun to listen to, I won't lie).
It might also help ease communication of most radio ops are on the same page when it comes to language or codes on the air. As a novice, I find myself having to quickly Google a few of the three letter acronyms I see used in many ham discussions, and I realized I'd lose that ability if the power ever goes out. This app is a nice little reference to practice some common ones in your idle time, so that you can at least have a few logged in your memory.
If you're concerned about drive space on your smart phone, this is comparatively tiny, weighing in at just over 850kb. I'm also not 100% sure about the accuracy of some of these lists, but the developer seems pretty decent about updating and correcting things verses some other app developers I've contacted. So, as time goes on, any inaccuracies should be fixed.
GCC - Geocache Calculator http://gcc.eisbehr.de/ (http://gcc.eisbehr.de/)
I just grabbed this one last night, so I'm still going through it's numerous functions. Don't let the name fool you, there are a lot of alternative uses for this app, especially if you're in the market for generating, deciphering or just learning about codes in general.
At a basic level, it's another code reference, accompanied by tons of calculators. As opposed to Signals (mentioned in previous reply), this one can actively create or translate found codes. The list of available codes and languages is pretty vast in this one, so for the sake of brevity, I won't list them all here. I did, however, find it cute that some fake languages are included, such as the "alien" language on Futurama and a few from various video games.
All of the calculators are pretty easy to use if you've got at least a basic understanding of cryptography. Morse is, of course, included in the mix, but one I'm really geeked about is the inclusion of the Enigma code, which speaks to my inner WWII buff.
There are some other non-code related functions such as a calculator for wind chill, as well as various coordinates calculators that could help a user pinpoint areas on a map.
In a STHF context, this could be useful for group communications either on the air or physically. If you're familiar with the "hobo lifestyle" (not sure what else to call it), you know that they do have a language of symbols that they'll mark on areas to inform other hobos of what's going on there. I've seen a few old ones in my visits to Chicago, generally marked on buildings. The symbols can mean things like "safe to sleep/camp here" or "food for working" or even "leave area quickly."
Having a private language or code for your group to use would be beneficial in protecting supplies and stores, I think. My good nature expects people to work together as much as possible to survive in the event of an emergency, but my realistic side also won't ignore the possibility some folks are just asses and will attempt to simply take what they want, and that could mean you've got to defend yourself and your properties.
After all, we humans have been using community markings forever. Having a way to quickly decipher what's being communicated could come in handy. Using this app is an easy resource, and if you practice with it for awhile, it wouldn't be hard to just memorize whatever code or language you wish to learn. That or transfer the info contained in it to a notebook that you could keep on your person.