I've long been a fan of Oregon Scientific's ATC5K helmet cam. It just has a more rugged, waterproof build than other action cams on the market. Plus it has an LCD screen so you can instantly play your footage back, something other action cams are lacking. I even included it in my list of top ski gadgets of 2009.
Problem is, since that time, action cams have gone the way of the greater camera market: HD. More specifically, they've gone full 1080p. So as much as the other features of the ATC5K were above and beyond, the lagging video quality was a reason to look elswhere.
Now it's time to give Oregon a second look. The new ATC9K features the same rugged build of the 5K--actually it's even more waterproof (65 feet), but upgrades the cam with 1080p capabilities. It also has a built-in microphone for audio, something that you often have to buy as a separate add-on. It also has a "G-sensor" which can measure air time for all those epic cliff drops. And it includes a 1.5-inch TFT screen and adds a speaker so that you can playback your footage with audio.
Plus, for those that can't always remember where their footage was taken by the time they upload it to a computer, the ATC9K will have a compatible GPS unit that can not only geo-tag footage but can also calculate distance and speed, turning it from camera to a camera/sports monitor hybrid.
The ATC9K costs $300. You can see the Oregon Scientific's ATC5K helmet cam here.