Skijoring is Norwegian for "ski driving," and it refers to a sport where a rider on skis is pulled by a horse, a team of dogs, or even a motor vehicle. I think it's similar to waterskiing in that it's extremely fun to do yourself, but not so much fun to watch; you can see scads of skijoring videos on YouTube to judge for yourself.
However, one clip we came across is pretty fascinating. This is 1955 Bavaria where a team of maniacs is engaging in motor skijoring, being towed by a bunch of Porsche racecars, an errant VW and (we presume) BMW motorcycles. If Petrolicious is to be believed, these nut-jobs are traveling in excess of 100 miles per hour: