I do a lot of mountain biking, and part of me can see the attraction to one of these cameras you can mount on yourself. You know, see where you've been and that. But I know as soon as I get one, the first thing I record will be me breaking my neck, so fuck that shit.
They cost 0, shoot in HD, you get a free mount for a helmet and a free mount for the dash of your car or wherever you want to put it. They can be submerged in water (not great depths, but enough for say, caving), they have a fairly decent night vision mode and can shoot photographs even at continuous intervals of 1, 3, 5 or 60 seconds.
No, I was not paid to write all that. Just saying...
There will be a lot of "Ohhhhh! That's what happened!" moments whenever someone finds a mangled corpse at the bottom of a mountain with one of these strapped on what's left of their head.