I would check out the GoPro HD Motorsports HERO Camera. Sorry don't have a link but you can Google it. Basically it does HD, it's wearable, waterproof, and shock proof. Costs around $300 though so if you need something cheaper look into Kodak Zx3 or Flip UltraHD (4GB) with Flip waterproof case.
i am a complete beginner at filming but i am very interested to begin and all my friends skateboard and snowboard so i would love to contribute by making great videos!