Picked up a rare NuBus card today from eBay here in Melbourne, Australia: An Apple Remote Access Server Card complete in box with all manuals and software.
I've taken a few photos of the box and contents for those who are interested:
Apple Remote Access Server Card photos
Essentially this is a four port RS-232 serial port card for a NuBus equipped Mac with Apple Remote Access server software to manage the dial ins. You had to supply your own modems.
I used to run similar hardware on a PC Server back in the late 90's (Cyclades 8 port for those who are interested) - that was expensive enough. I can only imagine how much the Apple version sold for!
When I get time, I'll hook the RS-232's directly to 4 x Macs and see if I can trick them into talking without modems in between.