Create a Human character on Agamaggan named Joeschmoe. (This is a server you do NOT want to play on)
Create a Human character on Archimonde named Joeschmoe then delete him. (This is the server you WANT to play on). Then on the same server make a char from the other faction.. lets say an Undead.
Open a ticket, tell the GM you deleted the wrong char, that you really wanted to delete the char on the Agamaggan server. You will get your char back on Archimonde and voila you will have your Alliance and Horde character on the same server. This exploit can also be used to change your char. names.
This will not last long because most likely the GM\'s are not getting into that much detail when they restore a character. But as this gets more widely known and used they will pass a MEMO around making sure that GM\'s check the other characters on the server before restoring. So use it quick. Enjoy.