For anyone in the northern hemisphere starting to think about riding ice and snow, Chain Reaction Cycles in the UK has a good deal on Schwalbe Marathon Winter Tyres 40-406 studded/spiked tires. US$35.99 for tires that list at US$80.

I will be putting them on my new-to-me 1996 Bike Friday New World Tourist once the weather gets colder. I will post updates after I have used them a bit.