Hey there, I did a quick search and didn't see another post that had this information in it.
Well, my character is an engineer and I hated the idea of having to go to the forge to smelt my ore, so one day I went to smelt some stuff in the engineering building in Dalaran and It was going to actually let me smelt! This is the spot I have been using to smelt ore ever since I found out. Theres a picture included. The reason why is that there is a forge on the other side of the wall. Thanks to all the other people who let in on good exploits. :-D
Also: the upload of a picture thing failed so heres a link
http://img11.imageshack.us/img11/6163/smeltv.jpg