Jim Jackson has just given a talk about Ethernet at the WYLUG meeting. How it works, and where it came from. It's interesting to look back at a time when LAN didn't automatically mean Ethernet. Amazing to think that people thought this token ring stuff was a good idea! Nowadays it's a no-brainer: if you want to network some computers, whatever sort of hardware they are (unless it's something very strange) you just buy some cheapo switches and wires and you've got Ethernet. The only difficult bit is making sure all the wires are nicely hidden in the floor or ceiling, if you've got more than a few hosts.
On a related note, Mark Pilgrim has listed the software technologies he considers essential. These things, like SSH and rsync, are just the sort of thing you take for granted once you've got used to them. To me, it would feel really strange deploying a webserver that wasn't Apache. Why bother with anything else? As soon as you start doing anything interesting you're going to need mod_rewrite or mod_perl or something that isn't just a basic HTTP service, and Apache has got all that extensibility, and a massive community behind it.