In this Youtube video, Jan Derogee demonstrates the possibilities of the Cassiopei. This device can be used to load programs via the datassette port 50 times faster then the standard tape speed, it has a I2C interface, 2 analogue inputs, a PWM audio output for playing back .WAV files (8KHz, mono, 4/8Bit) and a simple speech synthesizer.
Website: http://jderogee.tripod.com