RFDump is an open source tool introduced at the Blackhat Conference in Las Vegas 2004 and is designed to work with certain RFID reader hardware to read tags and display their meta information on your PC. The current version is V1.6. “It is a backend GPL tool to directly interoperate with any RFID ISO-Reader to make the contents stored on RFID tags accessible. This makes it possible to test robustness of data-structures on the reader and the backend-application, perform proof-of-concept manipulations of RFID tag contents, clone / copy and paste user-data stored on RFID tags, and audit tag-security features.”
Check out the RFDump website for detailed information and downloads.
(As a side note, if you want general information on RFID reading/hacking check out the slides from Joe Grand’s excellent presentation at the IT World 2006 conference RFID Security for Retail Enterprises.)