Just for fun, a cheap helmet cam idea.
I was using this in my car but moved to a 2 channel system. It is GPS enabled (Google maps), auto power on/record, looping recording and is very light. http://www.ojocam.com/
It's not weather proof but I don't plan on using it in foul weather.
Mounted it with zip ties after wrapping some extra bar tape around it. It does have an internal battery but I am not sure how long it lasts so I am powering it from my pocket with a small external battery pack that is tiny that should give me 4-6 hours of record time. I am going to get a 90 degree bend usb cable to streamline it a little.
I did not try to make it pretty and it only takes a few seconds to cut the zip ties to remove/reinstall. I don't have to remove it to retrieve the ride files.
Looks bigger on the helmet in the picture than it really is and I also have a handlebar mount. The little GPS unit can also pop off to make the whole package smaller but I like the maps feature and speed built into the video.