In reply to Tony the Blade:
> So, how would one get from the station to the col? I've only ever been down the track (with and without rope handrail).
Hello,
For those so inclined, instead of walking down the arete you can ski the south couloir (40 to 45 degrees for 150m) of the Cosmiques Arete after a quick 60m rappel down the final gendarmes leading up to the viewing platform. At this time of year, this is only to be attempted quite early in the day, before the south-facing snow has soaked up all the sun and turned to potentially-sliding porridge. All-in-all, I cannot recommend this approach unless you enjoy skiing steep slopes with 60m ropes on your back, and have quite a strange sense of humour in general.
With regards to the rest of the skiing/snowboarding at that time of year, it is pretty much peak season for all of the steep couloirs up high, but with the Grand Montets lift closed and the Mer de Glace turning into a rock garden, you have to be pretty fit and enthusiastic to make them happen (that is, a walk up from Argentiere, or skinning back to the Aiguille du Midi, depending on which spot you are in). There is absolutely nothing in the way of pistes or lift-served skiing available.
Oh, and there are two nearby Via Ferrata, one down valley above Passy, and one through the tunnel above Courmayeur. I've done neither of them so I can't comment, I'm afraid!