So I've got a client with m0n0wall running on a lame motherboard that
only has 3 PCI slots (all full of 10/100 ethernet cards) and needing more
ethernet ports now.

About 2 years ago when I was building a roll-my-own linux firewall box I
bought a d-link quad ethernet card for it, and things were good.  I don't
remember how much it cost, but it wasn't ridiculous.  It seems these days
the only quad 10/100 pci card I can find is the adaptec one, and it is
very expensive (and has a lot of features that we really don't need
anyway).

It looks like d-link stopped carrying their card, and googling hasn't
been very productive.  It's amazing how many hubs and switches match the
search terms, even if 'nic' or 'card' are included in the search.

Does anyone have any recommendations on how to expand this system?

Thanks in advance,
jim