Inverarity writes in regarding serial port projects for PCs – “There’s a great book for this stuff, Controlling the World with your PC, by Paul Bergsman. I loved this book when I was a young tinkerer (alas I have much less time for tinkering these days, which is why I live vicariously through Makezine.) Mr. Bergsman also used to write for Circuit Cellar, I think. The book has general tips for interfacing with the parallel port, as well as designs for driving LEDs, relays, stepper motors, and lots of other stuff. Great fun!” Link.