Since I don't want to have much more in the video setup than I have in the car, this is what I use:
Camera -
Aiptek A-HD+ (or similar), SD card based, can shoot 720p or 1080p QT files. This camera can be powered/charging while running with a simple mod to attach a 12V adapter to the supplied cable from the AC adapter. ~$100 Amazon.
A 32GB SD card will get you 17.6hrs at 720p/30fps, 9.4hrs at 1080p/30fps. So you don't have to mess with SD card changes during pit stops. The camera will automatically start a new file at the 4GB limit so you can literally set it and forget it for an all day run.
Mount -
Muffler clamp, crossbar drilled to accept a 3/8" bolt that has the head ground down to fit in the channel, clamped to a piece of innertube wrapped around the cage bar (to kill the vibrations). Manfrotto 482 micro ball head mount screws to the 3/8" bolt. ~$30 at a photo store + a muffler clamp. An enhancement to this would be to make a u-channel out of aluminum that clamps around the body of the camera and goes over the ball head stud to stiffen it up a bit (the camera itself flexes on the mount a bit).
If you want wide angle, there are wide angle lenses that will attach over the stock lens. I don't run these, because in order to see the driver, our camera would have to be back further than the main hoop.
Couple of examples shot from this camera setup -
http://vimeo.com/12385155
http://vimeo.com/12385531
Unpimp Ze Lemon1988 VW Scirocco
2010 North Dallas Hooptie 18th, Yee Haw, It's Lemons Texas 61st