vysean led some of our group on a snowmobiling tour out of Girdwood last March for our Spring Break Do. They all reported it was an absolute blast, and they came out with some awesome photos. Might send him a PM for the name of the outfit he used (I don't remember what it was).

Not sure what the dogsledding options are in winter. The weather's right for them, of course (well, sometimes--November can be hit or miss on the snowfall), but not too many tourists are here in the long, dark days of winter! I've got to hit the sack now, but if no one else has input on those, bump this thread back up and I'll take a look.