Speaking of action cameras -- there are still plenty of GoPros out there, but many of them are unusable for certain situations because of distortion or the lenses have been cracked (which would certainly render them useless). Instead of buying a new camera, there are a lot of third party manufacturers that make lenses that will fit these tiny cameras. Not only that, but the process is relatively straightforward, as you can see in the tutorial videos embedded below.
These both originally appeared on FilmmakerIQ. The first is a Sunex lens and the second is a Rage lens:
Video is no longer available: www.youtube.com/watch?feature=player_embedded&v=Fl49NTv7HjY
Video is no longer available: www.youtube.com/watch?feature=player_embedded&v=Lx-Uotq37nw
With the new crop of action or POV cameras, it's likely that modification will become more and more difficult as the hardware becomes more specialized and expensive. GoPro has a wide range of third party accessories and modifications that can help take your camera to a whole new level. You'll have to make sure that you buy the right lens for the right model, as there are a few differences between models and the specific lenses they can accept. Here's an example of the GoPro with a new Sunex lens:
As you can see there's a lot less distortion. These cameras are mainly designed to be mounted on people, which is why their lenses are so wide. If you want to use them just to take advantage of their small size, it helps to have a lens that won't exaggerate unnecessarily. There are many places to find these online, but you can check out which lens you'll actually need from the links below.