These cams are very popular with RC enthusiasts. On youtube you will see many ingenious mountings to RC airplanes and helicopters. On this link, Jelly Lens you will see just one example of a fellow who attaches the “jelly lens” to his Keychain cam. There is another guy on this video who uses a .67mm wide angle lens on his Keychain cam.
I just ordered a “909” which is the same cam, only a little sturdier housing, and a voice activation feature. The voice activation is 60db, which is actually quite loud, about as loud as a handclap. Around here, I need one that activates at the sound of a gunshot, or a scream, or two cars colliding. This ‘909’ cost me about $17. It can be had a little cheaper, but I wanted to make sure to get the #3 version.
One thing about the KeyChain cam is that they are very fragile. They break easy. The construction is very poor. I had one that lasted and lasted, and others crap out quickly. On the other hand, they are really cheap. RC modelers love them.