I'm now very excited about the prospect of picking up an Watch given the glowing reviews of how well the water resistance is holding up under real world applications. However, I'm most interested in what it can do with external devices. Pay is a given. But I really want to tap into the things Tim Cook was throwing on at the end there just before the release ... starting a car, unlocking doors, etc. I'm pretty sure I will have to buy a new car to get my existing security system to work with the Watch and my car door locks, much less the starter (but who knows maybe an add on bluetooth module that will mimic my key fob radio codes will do it, though I suspect the security protocol aspect will thwart that unless specifically designed by the car maker). But I should be able to buy an Watch compatible door lock now. You'd think. However, I'm having a hard time finding one. Has anyone started using their watches with a door lock, and if so, how is it performing, and what brands are you using it with?