NFC (Near Field Communications) is a way for two devices very close to each other to communicate. Sort of like a very short range bluetooth that doesn't require authentication. It is an extension of RFID, so anything you can do with RFID you can do with NFC. You can do more stuff with NFC as well, such as communicate bi-directionally with cell phones
Because it can read and write tags, you can always just use this for RFID-tag projects. We carry a few different tags that work great with this chip. It can also work with any other NFC/RFID Type 1 thru 4 tag (and of course all the other NXP MiFare type tags)
The PN532 is also very flexible, you can use 3.3V TTL UART at any baud rate, I2C or SPI to communicate with it. This chip is also strongly supported by libnfc, simply plug in an FTDI cable and use the FTDI serial port device to communicate - this lets you do NFC dev using any Linux/Mac/Windows computer!