Sumanth sent us a link to a DIY USB Bit Whacker, which can be built in about 10 minutes. You can buy commercial version, but if you have a PIC18F2550 lying around you might as well make it.
Calling the USB Bit Whacker a virtual parallel port is doing it a disservice; it’s much, much more than that. It gives you complete control of a fairly powerful microcontroller, the PIC18F2550, through a serial, command-driven interface. The entire platform is powered from the USB bus, no wall-warts or additional wires! In addition, all communication occurs through a virtual serial (COM) port, using the USB CDC protocol.
Read more about making a USB Bit Whacker