One of the things I was interested in for protecting my mancave was a smoke detector that connected to the Smart Home.  Nest Protect is one that does.  It is tied into my Wink Home Automation system, in addition to having the Nest App itself.  If the smoke detector goes off, it triggers alerts to my phone as well as setting off the alarm in the house.  (since my mancave is in the barn, not in the house)

This thing works well and doesn't suffer from issues the first generation of smart smoke detectors did.  (Like alarms you couldn't turn off if they triggered the wrong way).

So, yeah, this is just one more tool in my home automation arsenal.