Old Macs As Terminals

batwingTM asks: "Hey, I've have this old Mac Classic (the first computer that was completly mine) that I really wanted to do something with... It was suggested that I make it an aquarium (I remember After Dark for the Mac with "fish") but I also heard that it is possible to turn it into a simple terminal. I have a few Linux powered machines in the house and the thought of being able to access them from a terminal in the kitchen and/or bathroom seems appealing. So, I was wondering is anyone out there knows how this can be achieved?"