Having a standard smoke and carbon monoxide detector in your home is nice, but it's not going to help when you're not at home. If you have kids or pets, I'm guessing you'd want to know if something's gone awry while you're out. Nest Protect sends notifications straight to your phone if an alarm goes off or if its batteries get low — which means you won't be woken at 4 a.m. by shrill warning beeps. The device will also give you a heads-up before the alarm sounds, with yellow flashing lights and a voice telling you what the problem is. Plus, if you tend to set your old smoke alarm off a lot by cooking, Nest Protect can be silenced by merely waving your hand in front of it, meaning you don't have to clear the air by flinging a towel around.