Additionally useful because Rage gains cause a substantial amount of AE threat, which lets you use this ability on a pull to ensure all mobs come to you as well as giving you the ability to lead off with an attack when they do. Moreover, because it's a Gouge effect even against one target (assuming there's no bleed effects) it can buy you some precious time...
Intimidating Shout Description: A very, very useful ability that most people don't know how to use properly. Intimidating Shout him and you can stroll over and smack him in the face once Frost Nova wears off. Intimidating Shout his PET, then follow the Hunter around while the pet stands there looking like an idiot and you beat the crap out of his master (this also works with Warlocks or Mages with Frost Elementals! namely, enough time to use a full bandage (or close to a full bandage), which will help immensely when trying to kill difficult monsters or other players.
The target will stand there, unable to move or use any abilities, until they take damage of some kind (and yes, Rend/Deep Wounds will break the effect). Additionally, you generate more Rage from incoming damage while under the effects of Berserker Rage, giving you considerably more Rage (and therefore, options) to work with.
This ability, more than anything else, is why as a Warrior you will be in Berserker stance 90% of the time in Pv P - so as to have access to your fear break when needed.
This leaves Heroic Strike with a deceptively low listed Rage cost compared to the actual amount of Rage you spend.
Heroic Strike has two distinct uses, depending upon if you're using a two-hand weapon, dual wielding or a sword and board.
Additionally, special attacks cannot glance, which gives this ability an even greater damage bonus. Finally, when using a sword-and-board it's an effective threat generation ability that does not trigger the global cooldown.
This allows you to increase your threat output in situations where you are able to keep your normal threat rotation on cooldown regardless.
Cleave Description: Much like Heroic Strike, Cleave is an on-next-hit ability that will increase the damage dealt.
Most useful in groups where some or all of your party members will not benefit from Battle Shout's attack power boost, or in tanking situations where the increased survivability outweighs the increased threat/damage from Battle Shout.
Thunderclap Description: Thunderclap is one of the best Warrior abilities.
This one was a little bit longer because there is quite a bit of useful information!