I wrote this simple Processing sketch to illustrate how simple SparkFun's USB RFID Reader is to use.

The USB RFID Reader works with the ID-2, ID-12 and ID-20 RFID readers depending on how much range you need.

When an RFID is placed next to the reader it beeps and send the RFID's number via serial. If you have the Arduino software installed you can simply open up the serial monitor and see the RFID number.

This Processing sketch displays the product photo of the RFID being scanned...obviously this only works if you put the RFID number into the program, since every RFID number is different.