Have one for my and the spare key and they sit in them when in doors - like putting them in a tin. This way the key cannot be cloned from outside the house, as been publicised in the press.
Also when I go out the pouch comes to and when leaving the car and locking it put key back in pouch so again no-one can open the car if you are in range (I know the range on the audi wireless is not too far, about 5-6 ft or so, but I am a bit paranoid after loosing cars in the past).