I have an older laptop.
The one PCMCIA slot is being used to connect a DVD drive.
The one available RJ-45 Ethernet port is built-in.

There is WiFi available in this area.
I would like this laptop to have a WiFi connection.

Is there an external networking device that:
a. Establishes the WiFi connection on one side.
b. Has a RJ-45 port on the other side.
c. With a RJ-45 LAN cable, I can physically connect the RJ-45 port on the laptop to the RJ-45 port on this networking device.
d. So the laptop now has WiFi connectivity via this external networking device.

I am sure there are products that do this.
Who makes them?
Do you have any recommendations?

You could use a linksys wrt54gl with the dd-wrt firmware.
If you login to the router you can browse for other wireless networks and make a connection to it.

ps there are other routers you can flash with the dd-wrt firmware