NFC is in a lot of phones these days, but it perhaps isn't as revolutionary a feature as some thought it would be – not yet anyways. Sony is actually doing a good job of putting the technology to use with its SmartTags, but as with everything first party, it's more limited in terms of compatibility and functionality than some people would like.
Enter third party software. Google Play actually has quite a few apps now that will merge NFC tags with Tasker (or similar apps), an app I've previously talked about with regards to intelligent tasks. These plugins have in common that they don't care where you get the NFC tag from – old public transportation cards or simple promotional material would for instance work fine – it simply needs there to be a readable NFC chip with a unique identifier code.
So what can you use this for? Well, Tasker can automate a lot of things on your phone, and NFC tags can then be used to trigger that automation. Sony advertises the ability to mute your phone at night by holding it over a SmartTag, well, how about holding your Galaxy Nexus to an old bus card taped to your night stand and have the phone turn down screen brightness, mute ringtone, set alarm sound to full, and open the alarm clock app? Or use one in your car to active car mode, with a Bluetooth headset, music player, text-to-speech for messages and so on all ready to go when you bump your phone to your dashboard.
I must admit that NFC hasn't been on my list of priorities so far, but this use for it would actually intrigue me. Heck, I'd probably slap NFC tags all over the place if I had that option, like having one on my reusable grocery bag that opens my grocery list, have one with a trititum vial on it by my bed that turns on the LED, have one in the kitchen that opens the timer app, and so on and so forth. It's all about making your device automatically fit the situation you're in, and sometimes, bumping your phone against an old NFC chip is by far the simpler and more practical solution than GPS location, time of day, and so on.