I remember back in wrath and maybe earlier but I'm not sure, gold farmers would spell out URLs with the dead bodies of level 1s in Org and SW. I have noticed that this doesn't really happen anymore after Cata was released. Does anybody know why this stopped happening? I did some research but I couldn't find anything. It was a funny phenomenon that I kind of wish was still around.
If you are referring to game clients, then I think the max is dependent on your PC. In my guild there is someone you runs five or six clients at once.
Also, back when they use to do that "dead body spells word" they didn't stay logged in. I had an add-on called _Corpse, when you mouse over a player's corpse it tells you if they are online or offline regardless of faction.\