There's no shortage of smart door locks, but they typically require that you bring out your phone or enter a code to get in. Wouldn't it be nice if you could just knock, like you're visiting a friend? Candy House thinks that's a decent idea. It just unveiled Sesame, a smart lock that lets you get in with a secret knock on either your door or your phone -- you don't have to pull out a device, tap a number pad or even speak a command (though that's available) to open things up. The design should fit on your existing deadbolt lock within "seconds," and an optional WiFi bridge gives you both remote access as well as an easy way to determine which friends are allowed inside.