Electronics -- USB 8bit Interface Board
A small and easy-to-use 8bit parallel interface for the USB.
If you are after throughput (i.e. more than 800kb/s), then have a look at USB-FX2, a USB-2.0 "high speed" board.
Clearly, some software had to be written to test the device.
And of course, it had to run under Linux...
Furthermore, some utility to write/change the configuration EEPROM contents is needed for convenience. It turns out that this can easily be done from the USB port.
More information and source code can be found on the software page.