Certainly. I can come up with a bunch of reasonable-use scenarios too,
but most of the people here will have run into that awful situation where
a product is used in a manner that isn't "Recommended".
In this case, I know that some of these cards were marketed in the same
manner that workgroup hubs/switches are marketed; you would daisy-chain
these stupid things so that your PC would feed the cubes right around you
and then have an uplink and downlink a few cubes to the next "hub".
Remember, it was this strange time when people were uncertain about how
networks were going to evolve, and what the next thing would be, and
even then, 10baseT was being deployed over Cat3 (sometimes recycled/
repurposed), so any sort of "enabling" gadget such as these cards had a
tendency to be abused in various ways.
Two ports on each modular plug, though.... (shudder) 
... JG
To me, this is a Dilbert-class engineering failure. I would imagine that
if you could implement a hub on the network card, the same chip(s) would
work in an external tin can with a separate power supply. Designing a
product that actually exhibits a worse failure mode than 10base2 is ...
strange to me.
I have in my gear museum a fairly large box with a couple of this type of 'hub
on a card' installed. And in this particular case, it made perfect sense, as
the box is an Evergreen Systems CAPserver, and has 16 486 single-board
computers tied to two 8-port hub cards (two ports on each modular plug, too),
with....wait for it... a 10Base-2 uplink. These were used mostly for remote
network access and remote desktop access.
If you want more data on this old and odd box, see
http://www.bomara.com/Eversys/capserver2300.htm
I can see a hub card being useful in an old NetWare server setting, though,
since if the server went down you might as well not have a network in the first
place, in that use case.
Certainly. I can come up with a bunch of reasonable-use scenarios too,
but most of the people here will have run into that awful situation where
a product is used in a manner that isn't "Recommended".
In this case, I know that some of these cards were marketed in the same
manner that workgroup hubs/switches are marketed; you would daisy-chain
these stupid things so that your PC would feed the cubes right around you
and then have an uplink and downlink a few cubes to the next "hub".
When I had the need to wire a building around 1987, I opted for the multiport 10Base5 repeaters that DEC made -- they were called DELUAs, I think. I'd had quite enough of distributed single points of failure, thank you.
Remember, it was this strange time when people were uncertain about how
networks were going to evolve, and what the next thing would be, and
even then, 10baseT was being deployed over Cat3 (sometimes recycled/
repurposed), so any sort of "enabling" gadget such as these cards had a
tendency to be abused in various ways.
Right -- the wire and pin assignments for 10BaseT and 100BaseT were designed to permit sharing the cable between Ethernet and phone.
Two ports on each modular plug, though.... (shudder) 
Hey, I had that in my house on my 100BaseT network, till I upgraded to gigE and had to give in and buy another switch. (Sigh -- home network configurations of NANOGers. I'm contemplating putting in VLANs now...)
--Steve Bellovin, Steven M. Bellovin
In article <DAA7E8AD-EFFF-4076-85DB-1CDC19AFA483@cs.columbia.edu>, Steven Bellovin <smb@cs.columbia.edu> writes
Remember, it was this strange time when people were uncertain about how
networks were going to evolve, and what the next thing would be, and
even then, 10baseT was being deployed over Cat3 (sometimes recycled/
repurposed), so any sort of "enabling" gadget such as these cards had a
tendency to be abused in various ways.
Right -- the wire and pin assignments for 10BaseT and 100BaseT were
designed to permit sharing the cable between Ethernet and phone.
I wired a new-build house (of mine) like that in 1995. The CAT5 cable was expensive enough that it made sense to share. And it worked. The bigger challenge was getting Internet to the house, not round the house.
Ten years later, both voice and data would probably have been better done by wireless (DECT and wifi respectively).