We've been playing with installing a number of the cheap ($20) digital units with 16Gb memory cards as an option. Being tiny and light weight they are ideal for mounting in unusual places and best of all dont' need huge mounts to make them secure -- low mass
We've rigged a number of differnet mounts for differnet areas of our cars and await the arrival of the race season to see how good they really are. The beauty of 16Gb is we can turn them on and leave them recording from the time we start up in the pits.
Trying to get bulk-buy down to $15
BIG downside is all the buttons are "foutery" --- ie small and difficult to use Espsecially with race gloves or bike gloves on. Can't have everything and so far all recording have 5 minutes at the start fo "crap" while we set things up hjaving started them up before final preps.