Thank you for the reply!
I'm not looking to write to the card, just read it to determine whose card is being used.
Something similar to this reader:
http://www.amazon.com/CE-Compass-Magnetic-Stripe-Credit/dp/B008FW3XXG/ref=pd_cp_e_2
That works similar to this (except to light up an LED, not make money transactions):
http://www.ladyada.net/make/magstripe/index.html