The speedometer in my Jag is out of commission and it would cost me at least $500 to get it replaced.
But wait, there is a $0.99 (that's right .99 cents!) app for the iPhone 3G called "Speed" that can be used as a speedometer and it works! No wiring required, just open the app. on the iPhone and drive away. The GPS satellites will clock the car's speed past 5 mph. GPS is amazing but even more amazing is the 99 cents app. I would have paid $50 for it.