Game: Rift
System used: Players are given a suggested server to join but are free to join a different one if they wish
Source
See the pattern here? These are all standardized and acceptable ways to deal with underpopulated servers.
So why, why are you going out of your way to make this as much of a problem as possible? Why are we forced to divide communities and split because you're don't want to name the new servers and or give us a manageable system like every other MMO has done in the past... including your own?