I've recently taken the plunge and bought myself one of these not cheap but could turn out to be the best £199 ever spent and knowing its there if I should need it is invaluable
Another item that I seem to carry but hope I never use
The full info here:
McMurdo's latest Fast Find PLB sets new standards in Personal Locator Beacon 406 MHz location technology and builds on the phenomenal success of the 210 with addional features. The Fast Find 220 is a potential life saver; it is extremely compact and will slip into the smallest pocket. You can set off in the most remote locations around the world, and be confident of being able to contact the world’s professional search and rescue services. Fast Find should be carried as a last resort safeguard against any life threatening incidents that may occur anywhere in the world.
Features of the 220 PLB: