I have a DroidX (android verizon smart phone).

I carry 3 extra batteries (ordered from China, about $4 shipped).

Small charger that works from AC or DC. Also charges my two small ham radio batteries (we carry 6 radio batteries, 3 each person). Set of clip cords for charger so I can hook it to any DC source 6v-14vdc.

Far to many apps to list specifically. Mostly I like
RAINDAR shows real time radar and storm intensity.

Many map and gps apps.

We don't depend on it, but it is surprising how many hot spots we find deep in the back country. Mostly on hills...

Lots of reference material. first aid, ham radio, special maps, and a whole lot more.

We don't depend on it and carry GPS, Ham Radios and other stuff. We don't depend on that stuff either. But having multiple items to do the important tasks (navigation, communication, data retrieval etc.) is comforting.

Nomad.