In reply to SailorSam: I'd recommend the GoPro Hero 2, its HD, comes with a water proof housing and is very light.
You could go for the Hero 3 but it quite expensive and a bit buggy, I had to send my back because it kept freezing and turning it's self off, not sure if it was just my one but I've talked to a few other people and they're not too impressed with theirs. Saying that, it super light and the wifi remote/app is quite handy and the quality is amazing.