Today I discovered a sort of exploit while doing Wintergrasp. It is somewhat common sense, but as the writer and philosopher Voltaire once said, "Common sense is not so common."
After you die and are at a Graveyard waiting to spawn, you can right click the BG symbol around your minimap to teleport out, instantly rezzing you to full health and mana. If your hearthstone is set to the Horde or Alliance Inns in Dalaran you can get back to the fight within seconds. You even get to keep your rank.
Note: By doing this you run the risk of not being able to get back in if WG is full, but if you do this at a slow time you should have no problems.
I really hope this isn't a repost or in the wrong section, but if it is I'm sincerely sorry. I couldn't find anything in my searches.