Instructables user powerpants created a quick and dirty card reader interface with an Arduino. The Arduino decodes the data from the swiped card and transfers it to a PC over a USB serial connection.
This instructable shows how to use some freely available code, an arduino, and a standard magnetic stripe reader to scan and display the data stored on magnetic stripe cards such as credit cards, student IDs, etc.
I was inspired to post this after reading the intro to magnetic stripe reading and Stripe Snoop that is found in MAKE magazine Volume 1. That tutorial details how to interface a stripe reader to a game port interface, but I have a mac laptop, so I don’t have a game port interface!
There are a lot of cool uses for this besides just seeing what kind of personal information is contained on all the cards in your wallet (you’d be surprised). A friend of mine in college once hacked together something like this with Microsoft Word and a bunch of Visual Basic macros to automate computer literacy testing for the whole campus. Students could swipe their student id, the test would start automatically, and when they were finished the results were saved to a database. He was hired to administer all these tests manually, so he basically put himself out of a job after a month and got a promotion.