Snowbike

This is cool...

http://www.ktrakcycle.com/

http://www.youtube.com/watch?v=IvnU64S2Pho&eurl=

So far, all I can find is "reviews" that say, "Hey this looks cool," and nothing like, "Hey I bought this, tried it, and it works great." I won't buy until I see some real reviews.

The rear kit sold for $300 until the end of 2006. The new tag is $400.

The front skid is $200, but I'm not sure I want a solid skid. There's too much variation of terrain, even in frigid winter, from snow, ice, rock, dirt, and pavement. I would want a skid that goes around a tire so that on pavement only the tire touches. The penalty would be a much heavier bike, but I just can't see having a solid skid.
Overall, the setup pictured might actually be lighter. You lose weight from the front and add some to the rear. In spite of less weight, it looks to me like you need twice the effort. There's too much drag. Still might be worth it.