What exactly are you planning to do with it? Basically, the camera is already very robust and can withstand a lot.
Otherwise, I would recommend the Super Suit:
GoPro Super Suit Dive Case (Housing)
I personally also find the Shorty a good gadget:
GoPro Shorty (grip, tripod)
Depending on how long you will be on the road, a spare battery is not a bad idea.
And of course a suitable SD card is a must, otherwise nothing works ;)
Two adhesive mounts are also included with the camera. You can then attach them to your helmet, ski... ski...