I'm a fan of "multi-use" things...the type of thing that you can carry around with you normally, and also use in an emergency. You learn how to use it proficiently, and are almost guaranteed to have it in any case. Recently, I got a Blackberry. As long as it's charged (chargers, AA battery chargers and manual chargers are available) it has many uses:
* Phone (obviously only works if the towers are still operative)
* Map - pretty decent road maps, and this works even if the towers are down
* GPS - Works as long as the satellites have a clear shot
* Flashlight for close work in a pinch; I frequently use it to find my way around in a dark room.
* Calculator, unit conversions, alarm clock, calendar, etc
* Can be loaded with any number of sounds - animal calls, high-frequency sounds, etc and will reproduce them pretty well on the speakerphone
* Camera and video camera - also records sound
* Any kind of reference, notes, books or extra information you have preloaded; it takes micro SD cards, which gives it a theoretically infinite memory
*Of course, it can also be used as an improvised kubotan
The possibilities are endless. You could load sound files for emergency phrases in 10 languages, or pictures and recipes for edible plants...and this is in addition to any other software you decide to load. You could use one 2 GB micro SD card for all your personal information, and the technical specs on all your guns in case of a field repair...or detailed topo maps...or whatever you want, really, so long as you can read it later.
A Berry, Treo, iPhone, etc will all fulfill these roles - the big advantage is that these features add no weight, no bulk and are in something that you should carry everywhere, anyway. In peacetime, they're also really great phones, too! :icon_wink: