I think it is ridiculous, no, retarded, to think of preferring cable tagging to allocating a server area/room.
I actually did a search, there are plenty of such products, of which I would admit I have seen used before.
Tagging is used to help identifying wires that are constantly changing. Not to see if there are sockets available for new appliances. But I can understand newbies like one of my client who fears she will shutdown the whole building by pulling a plug on the extension. A compromise I am willing to execute, since the labellings aren't too many right now and in the foreseeable future.