As far as I understand it, servers are named by the sysadmin team. We deploy enough servers that naming them all individually isn't practical, so we use themes to name large groups of servers — right now, we're using constellations and world cities for web servers, species of sharks for MySQL servers, and pairs of things for mail filers. For instance, your web server "noumea" is named after the city Nouméa (capital of New Caledonia), your MySQL server "daggernose" is named after the daggernose shark, and your mail filer "chong" is named after Tommy Chong (of Cheech and Chong — "cheech" is paired up with it).
We've gone through a lot of naming themes through the years, especially for web servers… previous themes have included foods, beverages, models of cars, Greek gods, Chicago gangsters, sports teams, and characters from various comics. We use names rather than numbers since they're easier to remember and distinguish from one another… at the end of the day, "noumea" may not be the most memorable thing in the world, but it's sure a heck of a lot better than "webserver5733"!