Make your Arduino talk to the Internet and make a POST request.
Create a circuit that posts an action to your profile on the Open Graph.
Tap your RFID card to post an action to your profile on the Open Graph.
Passively streams your favorite music with the tap of an RFID-enabled device.
Create a circuit that pulls information from Facebook to your Arduino.
Takes a photo and posts to your Facebook with the tap of your RFID card.