There are all sorts of applications available that utilize a smartphone's
sophisticated technology to detect the presence of certain radio
frequencies and other presences. Specifically, I've seen phones that
pickup FM radio (with a tuner), radiation (RadGuard app for
Blackberry), magnetic fields,
metal
detector apps (that I've tested
personally) and many more. Boat-loads of potential that is just barely
being tapped.
What I would like is an app that can detect when your phone signal is
being actively jammed, and alert you that you may be in danger. This
way, when you hear a bump in the night and reach for your phone to
discover a "No service available; jamming signal detected" message
displayed on the screen, you have time to prepare yourself for a home
invasion.
To arms, men! Brace thyselves, and let loose the dogs of war!
(or call for help with a CB radio, it's really up to you how you choose to
prepare)