Using Tasker, I have one by my front door. I tap it on the way out the door to turn off Wi-Fi, turn on Bluetooth, adjust volumes and then set a lock code. When I get home, tapping it again turns off Bluetooth, removes the lock code, turns on W-Fi and then reconnects to my local LAN.
At the office I have one which on arrival turns Wi-Fi back on, turns off Bluetooth, lowers the various system volumes and double-checks that the lock code is set. When I leave, it undoes all that (to get me back into travel mode for the bus ride home) and then sends a text to my wife to let her know I am on my way home.
Then there is one in my car that, when tapped, turns on GPS and logs a "precise" location into a Tasker variable. I have another Tasker task set up to locate based on the variable value, which helps when I am parking in an unknown location.
Finally, I have a tag on my key chain with my vCard on it. You know, for the one time a year when I don't actually have my phone with me but I do have my keys.
Other than minor tweaks, I pretty much have not touched any of these since I programmed them a year ago. I was going to do things like program the home Wi-Fi key in, but then I realized that pretty much no one but my wife and me have NFC, so I am destined to repeat the password to everyone who comes over to the house.
You know what has been far more productive than all these tags (including the 20 or so I have sitting unused in my desk drawer)? Tasker. God, I couldn't live without that.