hi. long time reader, first time poster.
I read someone's post about using a flying mount to sneak into the opposing faction's area of Dalaran. After exploring for some time, I found out that you can use the opposing faction's portal to lake wintergrasp. Very nice for when your faction's portal closes and you don't want to spend 5 minutes flying to the battle. I only have an 80 alliance character so I can't confirm that it works for horde, but I don't see why it wouldn't. Hope this helps!