Not that Jeffs idea wouldn't work, but I picked up an Oregon Scientific ATC-2k for my son's kart racing. Fairly inexpensive and the quality isn't what you'd get fron the big dollar equip but very easy to operate and watch. We had sone vibration issues but a little work with some isolation padding and we were in business. His kart (Yam KT100) vibrates pretty good considering no suspension.

Here's a youtube vid of the camera in action
http://www.youtube.com/watch?v=zqFzRB4QJAk

Didn't make it to the Mid-Ohio event this past weekend but would love to find a place to get some of the mid-west NSR's together.

Dan