I bought a 'road angel' for my wife and she says it's the best thing ever, She travels all over the country for work and it takes her right to the door every where she goes. also has positions of speed cameras programmed in.
I've heard of people stealing sat navs from cars parked in places where they are going to be left for a while i.e. shopping centres, sports grounds and cinemas, then using the sat nav to find the persons home and breaking in because they know the owner is out. A good tip is not to call your home address 'home' call it Uncle Bob's or Big Dave's, somthing which is going to put a thief off!