From Nate Pangaro on How-To Geek:
After a long day of work, all I want to do is get in my car, drive home, and go to sleep. However, before I do that, I like to let my partner know when I will arrive home. Now, this is not hard to do, but it does take multiple steps. Thanks to this inexpensive NFC tag in my car, the entire process is automated with a single tap.