I am surprised that I hadn't known of these until now. I have a few PCI serial cards which have their ranges of usefulness. But RS422 and SCSI seem like a great combo for retro use in my G4 towers. If they added ADB also would have been perfect. It has a 50-pin internal SCSI connector and 25-pin external. Probably not hardcore enough for a server or multimedia but maybe ok for casual use. The serial ports are supposedly not Appletalk compatible, but they list a few MIDI devices as known working, which is what I want. Most recent firmware upgrade I saw was for G4s up through Quicksilver, and the archived FAQ says the card works under OS 9 and X.

Of course, it may or not be quite this easy! Anybody tried these who can comment? If I can score one for cheap I will certainly check it out.