Love/Hate: My Nokian Hakkapeliitta W106 studded tyres. Really, it's more like Hate/Love, because they're just so heavy. You put them on, and you know you're not going to go anywhere very quickly. At the same time, your chances of staying upright in crappy weather like today are infinitely better. All of the extra effort you have to put into getting the bike to move isn't wasted when you're going uphill in crappy conditions.
Love: Moose Mitts. I'm rocking the road version on the Portland right now. I can wear PI Cyclones in 20° weather and my hands are toasy warm. Love these things. Seriously.