The secret lives of magstripe cards

I love All Electronics, the Van Nuys, CA retailer that buys surplus electronics inventories and offers them to the public at discount prices. One of the items I acquired through them was an assembly from a credit card verification device - it included a circuit board with various ICs (including a DTMF encoder/decoder that I plan to mess with at some point) and a 2-track magnetic stripe reader manufactured by MagTek, Inc. From the datasheet, the interface seemed relatively straight forward: aside from +5v and ground, there were a strobe (clock) and data line for each track, and a common 'card present' line.