I love my GoPro Hero2. I've used it in the boat, on the motorcycle, and skiing, plus on nature hikes. As mentioned above, the fixed zoom makes the skier look distant if it is mounted in the boat, but the performance of the camera is great. It will shoot in HD quality and it also has settings for timed still shots. You do need QuickTime Pro if you are going to edit the movies.
I have the floating back door for my case (it will hold it up with any mount except the suction cup mount). For the pylon, I use the roll bar mount which is an accessory you have to buy separate. It comes with a headband and I've worn it while skiing numerous times. They sell a surfboard mount which is actually two adhesive mounts. The second one is for the safety lanyard. GoPro recommends using that setup along with the floating back door and the safety lock on the case if you are going to actually mount it to the ski.
Here's an example from behind the boat, and how they hold up in a wipeout (no comments on my hands' position please, lol):
http://youtu.be/f2gaC4H1vWU