Training & Nutrition - off season training

What are the best sports or activities to do in the off season.
I do lots of cross country skiing in winter time.
As some of us live where snow comes and makes riding impossible on the road and trails.

So like some advice if skiing is good way to maintain what i gained from cycling during the nicer time of year

If by XC you mean fast track skiing, either diagonal or skating, yes it's very good for you. The other thing that's really good is a set of rollers in a cool room or garage. Some people do a couple thousand miles on their rollers over the winter, not really that hard to do. The rollers really need to have a resistance unit to be good for more than recovery. Many people do some weight lifting in the winter because their biking time is lower and lower intensity, so have some recovery time left over.

Denver tends to have mild winters most of the time. I keep riding but I also throw in more trainer rides, additional strength training, and running. That and the occasional snowshoeing trip.

My favorite cross training activities are XC skiing, ice skating, and weight lifting.