Have one tag stuck to my kenu airframe car mount, once touched, it enables bluetooth on the phone so it pairs up with the car handsfree/audio, it disables mobile data (dont need data whilst travelling), slaps the media volume up to full etc etc
One on the bedside cabinet, activates two alarms, turns ringer volume down to near silent, disables wifi and mobile data (dont need these running from 1am til 7am) and a few more things.
The only downside at the moment is you've always got to have a tag to reverse those changes. We need proximity based NFC so when the phone is no longer in reach of the tag, it takes those changes away ... then I will die happy