Snow tires?  

I used to live in an area with a lot of hills and some mountains there the snow tires definitely helped. They helped me get up a lot of the hills where otherwise I would get half way or close to the top and then slide back down. Now I live near the ocean though and get less snow with no hills. Here it helps to but brings down my gas mileage a little bit so I don't put them on.

I think that for the most part they do make a noticeable difference. In some places it's even illegal to not have winter tires after a certain date. I just run a good pair of all season mud and snow tires on my vehicle and I find that they work just fine in deep snow and on icy roads. I'm too cheap to have two different sets of tires so for me all seasons are the way to go.

I don't bother with them. They don't make a big difference & I learned how to power-slide long ago. I spend years delivery driving in the slop so it's no problem. It's the other drivers that worry me.