IOGear uses the ALI chip on their combo card and says it is Mac compatible; this card is sold by OWC. However, I have no personal experience with it. Do avoid, however. cards with VIA chips on them- The firewire works, but not the USB, even if you download VIA's drivers for OS X. All these drivers did for me was cause my Mac to fail to boot.
In my experience, there are combo cards for sale on eBay that claim Mac compatibility that aren't. Also be aware some of the cards OWC sells - specifically their "generic" (cheap) one is not compatible with Beige G3s.