This is a utility I created for the Parallax RFID Reader/Writer (28440).
This is licenced under MIT, so you are free to copy and modify my code, just please attribute authorship to myself. You can find the documentataion for the module at http://www.parallax.com/sites/default/files/downloads/28440-RFID-Read-Write-Documentation-v1.0.pdf and purchase the module here: http://www.parallax.com/product/28440