After locking myself out of the house recently, I figured I'd better get onto the task of keeping some spare keys outside, just in case of emergency. And, yes, obviously "just don't forget your keys" is the first step in all of this, but there are several circumstances where you might find yourself at home, locked out, through no fault of your own, and it would be good to have spares available.
Then I thought, hang on a minute, my phone is a wireless communications device, and so is my garage door opener. If I could just have an app on my phone that triggers the garage door remotely, that would be ideal! Why hasn't anyone done that yet? Well, they have. You need to do some hardware hacking to get a Bluetooth receiver wired up to the motor in your garage, but once that's done and your phone is paired, it's pretty easy. I'm not super-confident with electronics myself, though, so I'm not sure I could do it without ruining my motor or at least voiding the warranty, but a setup like that would have saved me a bus ride and some embarrassment. Then again, so would a fake rock and some spare keys, but that's not nearly as cool.
Mokalus of Borg
PS - I can never think of where to hide spare keys.
PPS - Mostly because every place I think of seems too obvious in hindsight.