Others are obviously good, but whatever you're doing try dropping the weight and doing it on a bosu. The instability is uber useful as a skiing-oriented exercise. Basically if you were doing jump squats, do them on and off of a bosu. If you were doing lunges, lunge on the bosu. I have a TRX set up and I'll so lunges on one leg and use the TRX to support the other foot. Hell, even just STANDING on one leg on that thing will get to you after a while; do it while you're watching TV or whatever.
In terms of cardio, you can't beat the stairmaster - closest simulation you'll get to hiking up a mountain. If you add 5lb ankle weights you can even simulate ski boots!