For desktops there are PCMCIA slots for ISA and PCI bus available.

With the command cardctl ident you may get information about your card. If your card is not mentioned in /etc/pcmcia/config, create a file /etc/pcmcia/<MYCARD>.conf appropriately. Take an entry in the first file as a model. You may try every driver, just in case it might work, for instance the pcnet_cs supports many NE2000 compatible PCMCIA network cards. Note: it is a bad practice to edit /etc/pcmcia/config directly, because all changes will be lost with the next update. After creating /etc/pcmcia/<MYCARD>.conf restart the PCMCIA services. This may not be enough to get the card to work, but works sometimes for no-name network cards or modem cards. If you get a card to work or have written a new driver please don't forget to announce this to the developer of the PCMCIA-CS package David Hinds. Look at the current issue of SUPPORTED.CARDS to get information about supported cards.

Since not all cards are mentioned there, I have set up a Survey of PCMCIA/CardBus/CF Cards Supported by Linux.