Control Pretty Much Any Electrical Device With Your Computer

Over at DIY web site Instructables, user indestructable thoroughly describes the process of connecting an electrical device to your computer and controlling it with some simple programming. The set-up relies on a USB relay device such as USBmicro's U451, and you'll need some wire, wire cutters, crimpers, and nuts to hook it all up.
Control Pretty Much Any Electrical Device With Your Computer