Instructables user talk2bruce created the Arduino Internet Gizmo, a card reader that takes you to your favorite websites with a touch of an RFID tag.

A cool RFID music table has been created using Arduino, iPod, and RFID tags to make it easy to change albums by simply changing the RFID tag.

Both are based on ideas from Tonuino, an open source project aimed at turning Arduinos into MP3 players.

The project takes an MRFC-522 RFID module and explains how to interface it to an Arduino. In this case the Arduino in question is an Arduino Pro Micro chosen for its ability to be a USB host.