I don't know if anyone else will think this is cool, but I am the building a Giant Anthem and the hayes disc rotor has a minimum thickness of 1.52mm lazer etched into it. I love it when manufacturers permanently mark this kind of info. on their products.

Concur! My crank arm bolts are labelled with installation torque. Handy information encourages proper mechanics.

Note - automotive brake rotors / drums have minimum thickness / maximum diameter stamped on them too - helps eliminate problems.