Kermit! (shudder). I have some horrid memories of trying to deal with non-universal serial buses like RS-232, transferring files using ZModem or LapLink. Kids today have no idea how lucky they are, now we have a Universal Serial Bus (USB) that does just about anything.
If you're a kid of today who has to deal with business/carrier grade routers, you still need to know your way around a null-modem cable as they continue to be used as OOB access (and generally also as a file transfer mechanism if you mess up firmware upgrades through the more friendly channels).