One more device to have that I just bought is a satellite emergency messenger. EPIRBs exist but are expensive and, other than in emergency (which IS a big deal) don't do anything.
I just got the SPOT satellite messenger. It tracks your position by GPS, can send tracking messages that show up on the map (Google maps) so anyone can track your progress. They also have an emergency button which will send emergency request through their center which will contact appropriate authorities (USCG for boats), very much like EPIRB. It uses Globalstar satellites, and needs clear view of the sky (so works so-so in the city) - works perfect on a boat, though, as I tested it this weekend. Every message got through.
Spot Messenger > Home
is where they are. It requires annual service (at either $100 for basic emergency + on demand OK messages) or $150 for tracking. This must be good when all else fails, for the cost of good hand held radio, and has other uses too.