This one came out of necessity.
As someone who works from home, we rely on a stable internet connection. Yesterday, we were hit with a situation that put our internet out of commission. Luckily, the coffee shop across town has reliable internet, so we headed that way with the laptop.
At the time, we had no way of knowing if our internet was back up, but we had left our iPad (wifi only) back home.
The idea hit: use Find My iPhone to see if we could locate the iPad. If the iPad was found, that meant that the wifi network was back. Makes sense, right?
So we checked a few times, and we'd know immediately that the internet was still down. Unfortunately, it never came back, but as I woke up that morning and checked the email on my iPhone I realized that I had received an automated email saying "Your iPad has been located." NIce! The internet was back.
Of course this requires that you leave at least one iDevice at home, and 3G has to be off. Still, if you have an iPad and it's laying around the house, you can always check it with Find My iPhone. Of course you will have to set it up. You can find out how to do that here.