When you have to uniquely identify a thing, it is often useful to name it. And if the name is to have meaning, you should plan for it. Some use:
A naming convention you shouldn't have is naming for function. Your main web server should be DNS'd as www or web, but it should also be something else, so you don't have to rename it should it be repurposed. Having your webserver named "www2" while your mail server is "www" and your news server is "mail" is just plain silly.
Here's a more functional example: at my old place of work, we existed in a large inter-connected network, so the standard convention was this:
I worked in the Electrical Engineering building in room 241, using a Dell Wintel box with only one other PC there, so my computer's name was ee241pc1. There was an Apple Laserjet printer I used, and that was ee241a1.
Of course, I had it changed to Deskbox, as it was the box on my desk.