For those gardeners living in the United States, GardenWeb have created a Zone Finder on their site. All you need is your zipcode and the calculator will inform you of the gardening zone most applicable to your area. Very helpful if you live in the US. (Beverley Hills is in Zone 10 - it's the only US zipcode I know from the 90's hit show Beverley Hills 90210)

Australian's looking to understand what gardening zone they reside in can view this map which also compares our regions against the USDA zones.

UK gardeners can view their gardening zones with this tool that also allows you to see your region in the USDA zonal colours.