At my old university they had been using Greek mythological names (zeus (master server of course), hermes, athena, artemis, etc.) for a long time and later apparently metals and alloys (gold, silver, tungsten, etc.) were considered "cool".
Personally, I like to call firewalls names like hell, archeron, charon, cerberos, hades etc. For workstations, the TV series Charmed has been a source of inspiration (prue, piper, phoebe, paige, leo, etc.) but I've also had a machine called fishtank. The latter was a HP X-terminal on which xfishtank was run a lot :e Come to think of it, the huge but crappy monitor of that thing is probably beter filled with fish than with a cathode ray tube *nudge nudge wink wink say no more* :i
Alphons (just chipping in)
P.S. I've also named machines after high performance parachutes, e.g. extreme, velocity, vengeance, stiletto, katana, xaos, lightning, etc.