The Nokian Hakkapelita tires are studded road tires designed for use in cities that plow their roads. It has the studs placed along the outside so that they do not contact the road unless you need them. They're really pricey, but don't buy cheap studded tires, they will wear out in no time and cause lots of flats.

The other option is to make your own. The guy who owns the LBS keeps telling me he is world ice biking champion.. not sure if its true or not but he is a hard as nailks ex messenger... anyways, he makes all his own studded tires. He told me he put so many screws into his tires once that his wheel weighed 7kg! I've never done it myself, but the dude says they are better than ready made studded tires, albeit less durable and more dangerous to your legs and the fork, and rear triangle.