After unsuccessfully searching the raspberrypi.org forums for DrDaq I came to to PicoTech forums and discovered not only a forum but drivers too...maybe you should "advertise" a little?
I'd like to use "old" sensors and parallel port DrDaq with the Raspberry Pi but see that you have discontinued the parallel to USB adapter cable.
There has been some discussion on raspberrypi.org about using the GPIO for parallel port connectivity...would this be viable as a means of (schools) continuing to use DrDaq technology for sensing?
Are you contemplating releasing a DrDaq-specific parallel to GPIO cable and driver? Or can you publish the necessary specifications to enable others to create them?