I recently purchased a Tysso MSE-750 Magnetic Stripe Encoder/Reader and decided to write a library to communicate with it in C++. I just started the project over at Google Code, which you can find here. Right now it can read 7-bit and 5-bit track data. I'm going to add the ability to write tracks next.
The MSE750 follows the MSR206 protocol, so the library should be compatible with any MSR206(or its derivatives like MSE-750) encoders.