I bought the best one that
www.helmetcamera.com can provide back in 2002. You can hook it to a camcorder, digital camera or anything with rca input's and use it where ever you want to record. Its waterproof and comes with a billet aluminum hard shell camera cover and has a curve on one side that match's the curve on damn near every helmet out there. I even hooked it to a VCR and use it for surveillance (done that before and worked mint)..
I bought it brand new, paid over $420 for it in '02 and used it on the bike once.. 1 FUCKING TIME!
Now that Im riding MX again I want to be able to record on the track, but dont have a camera small enough to hook it to. So Im selling it..
Comes with all of the following
1-Bullet camera (about the size of a lipstick tube)
1-Billet camera housing
All the RCA cables
1-Super small microphone (and very sensitive)
1-Plastic carrying case with foam inside (cut for each piece in the kit)
1-Battery pack and plug (holds 4 AA batteries)
1-Battery charger (came with the orig battery pack that was no good, they warrantied it and gave me the one that holds the AA batteries)
I also have a cigarette lighter power cord for car truck use, and another set of terminals to hook directly to the battery on your motorcycle, quad.. w/e to override the battery pack.
I have extra 200mph velcro that you mount the camera with, this also goes with it.
Its 100% everything you see in this image right from the helmet camera website.

Asking $200 +shipping