Mini Lens /Pencil Camera

I have just got back from a mountain bike holiday in the Alps and saw a few people with "Pencil Cameras" taped to their helmets. I am led to believe that these are additional lenses for a digital camcorder, the camcorder being stored in the (relative) safety of a rucksack. Is this right?

If so, how much are these cameras / lenses and where can I get them from? Do they need any special inputs on the camcorder? I am thinking of buying a digital camcorder and want to make sure that, if practical, I could use the pencil camera attachment.


If what I saw was something else, what was it, and what is the best way of using a camcorder to film biking / climbing footage (short of gaffer taping the entire thing to the side of my head...)?

Any advice greatly appreciated.