It turns out that Garmin don't just make satnavs - but they're also competing with the likes of GoPro in the "small camera for filming dangerous activities" market. Their current flagship product is the VIRB Elite Camera, and I got a chance to check it out at Gadget Show Live.
So in addition to a camera, there's also a screen on the device itself for a live preview of the pictures it is shooting - or watching back what you have shot. And if you don't want to watch on the device... you can even stream the video, live, to your phone.
Here's a video of me talking to a Garmin representative about it:
What's also cool is that there's a built in GPS - so you can not only log your journey but also overlay on the screen exactly where you are. There's also a (sold separately) heart rate monitor you can wear - and have the video display your heart rate on the screen as you jump out of a plane, or whatever extreme activity it is that you do.
The only downside is battery life and price - with it only carrying around 3 hours of juice for £350. Still - looks like an interesting device and a worthy challenger to GoPro hegemony.