I've thought about bringing this up a few times, but never got around to posting it...seems like now is a good time.
I've been doing nearly 100% of all this years hiking/backpacking by myself, and while this wasn't something that I even thought about all that much, it was sometimes worrisome for friends and family. So to appease the loved ones and also give that little voice in the back of my mind a rest, I purchased a SPOT satellite messenger.
For those of you not familiar with this thing, it cost me $150 for the unit and it is $100 a year for the service, and basically allows me to stay in constant touch with whomever I want or need to, including sending a signal for help in an instance such as the one above.

SPOT has three buttons on it.
1. An "okay" button that when pressed will send emails/text messages to everyone you have entered into your program saying basically "everything is fine, don't worry" (you enter the text you want...mine actually asks for pizza to be dispatched to my coordinates!) and also with a link to Google maps which shows exactly where you were when you pressed it. Everyone breathes easy and knows you made it to your destination.
2. The second button is "help". This buttons sends a message to everyone saying you are in need of non-life threatening assistance. Basically alerting any knowledgable or useful people you may have assigned that you could use them about now. This function keeps sending them the message and a google map of where you are in intervals, in case you are moving.
3. The third button is "911". Press this one and not only does everyone on your list get a message saying to rally the troops, but it also goes out to the local search/rescue/fire/police to get someone out to you ASAP. Again, everyone knows exactly where you are and it tracks your movements so you don't have to stay put in a dangerous situation.
For an extra $8 or so bucks a year it comes with $100,000 dollars of insurance to cover your rescue...meaning that for $108 bucks you can rest assured that you are always able to get help and almost more importantly in most situations, let everyone at home breathe easy when your doing fine. I figure I will go on about 10-15 backpacks and more than 30-40 hikes this year minimum, meaning I will be paying about $2 a hike for this comfort...seems like a pretty good investment to me.
For a couple extra bucks you can turn on real time tracking allowing people you have given a passcode the ability to log on and watch you move along your route...tracking your progress. This of course counts yourself and adds a new way to check your trip details.
It weighs about 7-8 ounces and is less than 4.5" x 3".
For those of you who want to know more about this thing...check it out here. http://www.findmespot.com/home.aspx
-aaron
"Nature does not hurry, yet everything is accomplished." -Lao Tzu