I just bought a GoPro Helmet Hero HD. LOVE IT! Great exposure and high-speed processing. No pixelation. Can do still photos too. There are multiple helmet mounts and a headstrap mount too. Oh Yea! Get the LCD backpack, replacement lenses and the tripod mount too.

The camera comes with a waterproof sealed housing. That's the one you use outside in the weather. That's the "bomb-proof" one. It also comes with a non waterproof housing. That one is for really hot and DRY weather to let the camera stay cool.