Coming from Singapore, a country with a lowest recorded temperature of 67 degrees Fahrenheit, I don't have near as much winter credibility as many of you living in colder climates. Actually, at my house in Northern California I don't really need to worry very much about my pipes freezing (I do worry about my Papaya, Pineapple, and Citrus plants getting too cold).
My friends use these faucet covers at their house in the mountains where it does snow and freeze. These covers are an elegant solution for protecting outdoor faucets from freezing. They are easy to use and more attractive and effective than wrapping the faucets with newspapers and blankets. This was bought at TrueValue Hardware, but they have some similar things at Lowes, Home Depot, and even at some Walmart Stores.
The main body is made of 5/8 inch expanded polystyrene. A single piece foam gasket allows the cover to provide a good seal against uneven surfaces. They don't take up much space in storage during the warmer months, and they should last for many years.
The locking nylon sliding grip holds the cover tightly in place yet is easy to connect and remove. This approach to locking the unit in place is much better than similar products which use thumb screws.
These covers are made in the USA, and have instructions in English and Spanish.