Skadd inside the secret room in Orgrimmar
Of course I didn't discover this on my own, I first learned about this on this amazing blog; Syrco Owl, and with these directions it was quite easy to manage my way to this secret room.
There isn't really much more to it than what you see in the picture, a small room, with a single candle on the floor and a big plate on the wall with the initials WKM, and a shaft for entering/exit.
The room itself is inside a giant stone pillar between the Valley of Honor and the Drag, as far as I have learned nobody knows what WKM stands for, it is most likely a shrine in memory of someone (Blizzard have done this before in memory of employees that have passed away) or maybe it's just a game designer that wanted to make this for fun, just to make us wonder why it's there? After all it's good to have some mysteries left, even after Cataclysm!
Inside the rock on the top of this pillar is the secret room
The pillar shown on the map