The GoPro cameras, with their versatile mountings and designed for difficult environments, are popular with extreme sports enthusiasts to capture the action from the handlebars of a bike, the helmet of a hang glider pilot, or just under the kick-board of a kite-surfer.
Connecting over Wi-fi, the WP8 client acts as a remote viewfinder for the camera, as well as allowing users to alter all the settings of the camera. While the app is available for every WP8 handset, Nokia have one exclusive additional feature, allowing the camera on a Lumia to take a picture which combines the GoPro picture, and a picture from the camera on the Lumia handset.
One note from the directory listing, in terms of compatibility:
The GoPro App is compatible with Nokia Lumia 920, Nokia Lumia 820, HTC 8X and similar Windows Phone 8 devices that have at least 1GB RAM. Requires Windows Phone 8.
What can you do with it? Well, there's a bit of editing afterwards, but here's the sort of action and quality that a GoPro camera can record.
This is from the 'video of the day' section on the GoPro website, and if you have the client on your phone, you'll have direct access to this area, as well as the picture of the day.
The GoPro WP8 client is available for free in the Windows Phone Store.