This is a very vague question, can u be more specific.
however if your objective is to simply exhibit control using parallel port, then i guess a serier of 8 LEDs opto isolated by opto couplers is a good enough and a practical project. as LEDs can be easily changed with relays, solenoids and other switches used for control operations by simply inserting level conversion circuits inbetween the circuit and real applications. hope u get what i mean to say