I never thought of that. That is a cool application.
With my iPhone I have Reminders app (which is location aware) set to remind me to turn off ringer when I get to work and turn it back on when I leave work.
It sounds like with NFC, the phone would simple do the switch itself instead of having a reminder for me to do it. Sounds great! Although I wonder how that would work since most phones have a physical switch for ring mute.
Most phones actually don't have a physical switch for mute. It isn't needed on Android. Simply swipe down and tap or utilize a widget toggle on your homepage. Those physical mute buttons constantly fail on iPhones (just like the home button).
NFC is nice if you want to change phone settings, but it really comes in handy if you have guests come over to stay at your house. Place an NFC tag in their room, preset to a guest account for your internet and you don't have to worry about giving someone a login or password. They just tap their phone to the tag and done.Easy.
Let's say you are going to another country on holiday. You can copy your passport information and encrypt it onto your phone or a tag. If you lose your passport or have it stolen, all your info is there and can be used to produce a temp passport until you get home by the local consulate.
Let's say you are going to let another person use your Android device, but you don't want them to have access to your info and say they want to visit a site and type in another language. Tap a tag and all the settings change, including a new keyboard in the language that is desired.
Themeparks can use tags for maps and directions to attractions. For specific ads. For trolly or unirail times and locations. NFC can replace paper tickets, notify you of line times and so forth.
There are millions of uses. Going to Google I/O in March. I'm sure there will be plenty of NFC tags on booths and at the front door for you to easily download product information and give grouped internet access to different access points, preventing all internet from getting bogged down. Access to this local wifi can expire at a certain time as well. The next day, you get new wifi protocols. Tags can also be used for directions back to an individual point of interest.
Apple was stupid not to incorporate this tech. NFC is not just for paying for things and passbook is a pale joke compared to NFC capabilities.