In reply to Mark Bull:
I got rather over-interested in responding to this properly as my Mother & Sister live in the area, so I'm there alot.
In both ski-touring routes below I would advise taking winter climbing gear to whatever degree you feel comfortable as well as avalanche trackers + ski crampons a must.
Take the bus up the Giffre Valley (via Morillon and Samoens) to Sixt-fer-a-cheval, carry on up to Salvagny ski pistes. Go up the Cascade route under your own steam (if that wasn't clear) to Lac de Gers (stop at Lac Gers resto for lunch; absolutely beautiful, no lifts, only ski in ski out, good bunks too if you have too much Eau-de-Vie). Carry on up to Tete Pelouse (not summit unless you know what you're doing), then on to Les Grands Platieres then over the Col de la Portette (work your way round to the East side of Pointe de Platé and look over the edge if you want a rush!)Refuge de Platé not far away (but don't know if open in winter,check). If you've enough juice left ski back to Flaines via the Col du Colonney. 13kms up, many down, very steep start for 1km but then fairly easy gradient all the way up. This is one of the best routes on many levels that I've done in the area.
For something a bit more committed in degree of difficulty: from Samoens (accessible by ski pistes from Flaine) is the Col de Bostan to Tete de Bostan ascent (stay at refuge de Bostan-Tornay) with the Terres Maudite-Pas de la Late-L'Avouille to Col de la Golese ridge & shoulder descent. The last 3kms descent to la Golese is one of the best in the area, with the right snow conditions as always! You can take some serious air if you know where to go, but I'm not telling (if you're experienced, you'll find it). Buy local Randonee Maps and guide books in Samoens, ask at local guide office for conditions of the route. Have fun-be safe!