If you are interested in RFID and want to experiment with it, I strongly suggest you take a look at Parallax's RFID Reader Module. At $39, it is an affordable way for you to have fun with RFID. It is a read-only RFID Reader that reads tags up to 3 inches proximity. Connection-wise you need a serial cable (you need to convert the TTL interface to RS232 though) and when a tag is detected, it continuously sends the tag ID to your application.
I want to express my gratitude to Ryan Clarke (from Parallax) for his help in getting me started with the RFID reader module. He has been very patient in guiding an hardware-idiot (that's me) and for this I am very grateful to him! Thank you, Ryan!