/cast [target=target,harm,nocombat] Battle Stance;[target=target,harm,combat] Berserker Stance;[target=targettarget,help] Defensive Stance
/cast [target=target,harm,nocombat] Charge;[target=target,harm,combat] Intercept;[target=targettarget,help] Intervene
what it does-
If you are out of combat and have an enemy selected, it shifts you to battle stance and charges. If you are in combat with an enemy selected, it shifts you to zerker and intercepts. I know that much works. As a bonus, if you mash the macro it goes battle--->charge---->zerker so you don't have to waste time going zerker manually. I'm not sure if the intervene portion of the macro works as intended, I don't have intervene yet and can't test it.
lemme know what ya think!
I use a very similar one for pvp. Came from 'wow warrior macros' on www.tankspot.com. Lots of other useful info with one the the best warrior tank guides - Fortifications by Ciderhelm.
http://www.theoryspot.com/forums/user-interface-addons-macros/31899-wow-warrior-macros.html (http://www.theoryspot.com/forums/user-interface-addons-macros/31899-wow-warrior-macros.html)
I've found the 'Fear Dance' macro especially helpful on Nightbane.
Site also has some cool videos of silly damage from Shield Slam - 8k in one.