To do this will require some electronics knowledge. There are basically two ways to do this:
1. Buy a kit that comes with basically everything that you need to do this. This is bad because it is heck of an expensive thing to buy. And you only get the power to do stuff that the manufacturer setup in it. Which in most in-expensive kits just allows you to turn stuff on or off. Where if you do it yourself you can also hook up temp sensors to a A/D converter and take readings, or for that matter any analog data.
2. Build your own. Using multiplexing and demultiplexing of the parallel port and some radio frequency transcievers to transmit data from your computer to the particular device you want to control. Bad because it is time consuming and can get pretty expensive. But the major plus is you have total control on how the system works and how you want to make your program.
I did something similar (minus the RF stuff) to control lights using the parallel port to turn on transformers to turn on relays (The parallel port cannot sink very much current).
I recommend though that if you are messing around with the ports on your computer for controlling stuff you should add an opto-isolator so if your circuit (or the one you buy) fries or surges it will not take out your port as well.
Also does not have to be the parallel port, can be serial port, USB, depending on how you want to implement it. Can use your computer to communicate wirelessly to a microcontroller (or a few of them) to control different stuff around your house etc.