• mythology gods
  • sci-fi authors
  • cities, countries, lakes
  • fishes, shells, flowers, sweets
  • drugs (yes, I once ssh'd to tetrahydrocannabinol)
  • chemical elements
  • fiction characters, like Asterix, LOTR, X-Men (good guys being Debian servers, magneto being the Windows server)
  • female first names
  • boring names like mailgw012

I wonder what else people use, if people know other naming schemes I'd be curious to hear them.