1. Satellite phone
2. GPS
3. Spare batteries
4. Waterproof bag for all of them.
Seriously though.
This is my 11 essentials list, a bit more than ten items, but follows the general idea:
1. Map/Compass
I use a Sunnto similer to the MCA/MCB models. It's small, light, and the mirror also becomes my signal mirror. (multi-purpose)
I also carry a 2AA etrex Garmin Legend C GPS now.
2. Flashlight (headlamp)
Petzl MYO XP. Lightweight, 3AA batteries, 1 watt LED, 4 modes and a turbo button. A great headlamp.
3. Knife (IMHO, you really shouldn't need more than 3)
Used to be usually a Leatherman Charge and a Benchmade Nim-cub on my person, with a plain edge SAK one-handed trekker in my bag (when I travel with others I carry a SAK Soldier in my pocket, in case I need to give them a knife). But, I want to change the Nim-cub now that it was discontinued.
4. First aid kit (Varies way to much to list, but I assemble it myself in a small bag) Bandana/Triangular bandage included in that.
5. Fire starter
On my person I carry a BSA hotspark and a Permanent Match, with a little vas/cotten in a bag in my wallet. I carry more in a film or match container in my pack. Sometimes I carry a mini-bic too, since it takes up no space and is simple to use.
6. Signal device (whistle and mirror)
Whistle is Doug Ritters flat Fox 40 design.
7. Water purification/Water bottle
I carry a Camelbak with two nalgenes nested in a metal cup and lexan cup on the sides. With that I carry katadyn tabs and a survival straw also.
8. Insect stuff/Sun screen
100% deet with a permethrin mix right now, sun stuff I usually don't carry (around here).
9. Hat
military type full brim hat
10. Rain gear (big plastic trash bags are multi-use and excellent rain gear)
A few big trash bags. I usually precut one for me and my pack and just reuse them.
11. Toilet paper
Charmin, but re-rolled so no carboard center
Now, that list doesn't include spare clothing since that is a completely seperate list. I also didn't include weapons, since NJ isn't big on them and I do most of my stuff without them, but I would want something if I went a bit further out into the country.