I mounted my digital camera to my car today and took a few movie clips of it cruising around my neighborhood.  My camera doesn't have sound, so you can't hear the whine of the motor, but I through in a cheesy disco soundtrack and edited the clips into this short movie.

If you have a decent digital camera that you care about, I wouldn't recommend using this approach for on-board video shots of your RC car.  One crash and your camera could be toast.  I managed to get away with only a few scratches, but one more rollover and I might have been forced to look for a new digital camera.