By using the Parallax RFID readers (for cheap, remember?) and an Arduino, [Matt] is able to parse an RFID tag, look its number up in a database, and then have a computer announce “Access Denied ...

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 tape can be selected and placed in the player, and the Arduino at the center of it will recognize the tag and play the corresponding MP3 file stored locally on an SD card.