One of the things that always tickled me in MediaMOO was the way that you could hook up a computer in your room, then climb in it, navigate through DNS like tunnels, and climb out of someone else's computer.
And there were rooms that functioned like mass transit -- a monorail I think?
Loved the elevator on LambdaMOO. Push the button to go down to 'hell' floor or whatever. Watching my friend work on programming around that kind of stuff taught me the basics of state machines and so on that took me from "played with BASIC & Pascal & Modula-2 as a kid" to "Sure, I'll write your CGI scripts and JavaBeans or whatever" and got me working in the industry eventually...
And there were rooms that functioned like mass transit -- a monorail I think?