I am interested in showing how useless these are Rfid chips really are. I have found some information about people building cloners but the design that I have found looks like it could be ported to Arduino. Check out this link http://cq.cx/vchdiy.pl
it looks like real fun to build such as device.
I'm amazed how much rfid is being depended on and there are storys about someone making a $50 dollar cloner and the controversy that followed (google 'defcon $50 cloner'). However I can assure you that I'm not searching for such. I may go missing in the night!
If anybody is up for working on such a project please let me know. I have seen a video of someone using a Arduino to do magnetic cards using a ipod, but such technology is so generic.
Basically the more heads on board the better! I look forward to hearing from anybody interested.
Snipez (White hat)