Hi Tom,
I'm not using one at the moment, but I may be in the market for one to use with a digital camera on my G4 tower.
Found this one on deal at OWC
USB ControllerAnd this one:
Another oneThe previous version of the Sonnet Tango card worked flawlessly on my 9600, which gave it Firewire and USB 1 capability.
This one is the later model of the same card with USB 2.0
HTH,
Chris K