John:
I use an IO Port roll bar mount with an old Canon Elura video camera. The Elura has a provision for an external mike (which I highly recommend) and I use a simple lapel mike clipped to the lower part of the passengers seat belt where it's out of the way. As mentioned the onboard mike picks up a tremendous amount of wind noise that's very annoying.
The IO Port mount is extremely flexible as far as positioning the camera goes and, with a light camera, very rigid.
Here is a sample of one of the tapes from this past summer with the Colorado club.
DonC
Terrific video. Really gives you the feeling of being there. Love the stereo sound too. That's really just from one lapel mic? Almost sounds like two mics and one is *slightly* out of phase with the other.