Attractions to visit in Japan in Winter?

What attractions in Japan are most worthwhile to visit in Japan in Winter? I have found the Sapporo snow festival, but can't find many other things major that occur during Winter...?

Locals find the food, hot springs and skiing attractive in winter. Otherwise, I suppose it depends on what you seek or what you are used to.

There are many winter festivals in japan, it's just that they aren't well-known and can be hard to get to.
Nozawa's Dosojin:
http://www.snowjapan.com/e/features/features-75.html
Namahage:
http://japundit.com/archives/2006/02/17/2005/
Kakunodate's Hiburi:
http://japundit.com/archives/2006/02/18/2006/
Yokote's Kamakura:
http://eng.e-tohoku.jp/05w/akita/03/index.html
Just for a start. I've never been to any of these but would like to someday!

Go see the monkeys at Jigokudani Yaen Koen near Nagano. Easily reached by bus from the front of Nagano station or train from Nagano to Yudanaka and bus from there. About a 30' walk from the road in.
The other highlight is the ice cruise at Abashiri which runs in February when the pack ice is passing by. Long way to go but a very unique experience and if you are already in Sapporo why not.
http://youtube.com/watch?v=1UVBe3EPAJk

Here is some photos of my trip in February 2006.
http://www.flickr.com/photos/glen1079/sets/72157604700573337...