Disclaimer: I've searched for posts on this spot, but was unable to find any. Please flame gently if this is a repost. My search-fu is weak since I've had all of 5 or 6 hours of sleep this week. :P
Was fairly bored last night, so I started jumping around SW to see what I could get to and what I could not. Besides the boring old uninstanced prison that doesn't go anywhwere, I found a way up to the platform behind General Marcus Jonathan that could potentially be useful for ranged Hordies to gank flagged Alliance. It seems to me that once up here, a Hunter could make use of Eyes of the Beast to run their pet into the Trade District to trick more Allies into flagging. Or a Priest could Mind Control guards from up here. There are a number of possibilities.
You'll want to start at the far righthand side of the outer wall. This route is to avoid as many guards as possible. Skip this if you're Alliance and just want to explore. Take the standard route to the top of the outer wall. You could run along the top of the wall and gank from above the gate, but a lot of people know how to get up here, and there is no escape route.
Hop down on the inside of the wall and follow along the side of the pond in Valley of Heroes, ending up beneath the gryphon entrance.
Next, jump your way up the hill until you're a bit above the first ledge of the wall, then jump down onto it. Run along the ledge towards the gates.
Here's where it gets tricky. You need to sneak past a guard or two, and probably some player. An Invis pot may do the trick, but I don't know if it'll really be adequate for our purposes. I trust the resourcefulness of the MMOwned members to find a way.
Then you want to get to this spot, and begin the walljumping Olympics. Your goal is to go up the tower as close to vertically as possible.
Once you're at the right height, turn and face toward the platform and turn run back on. Jump onto it. You don't need to land on the stone blocks for it to work. I just did it because I was playing around.
Congrats! Now you're in a spot that's very difficult to get to and large enough for you to move around to LOS ranged classes that are trying to kill you. As an added bonus, when you're ready to get the hell out of Dodge, you've got an escape route. Go back to the tower, jump up a couple times, and look down and to your right. There's a hole there you can jump into that leads under SW.
Don't bother trying to go further up the tower to get onto the blue roof. If you jump onto it, you'll just fall right through it and end up beneath Stormwind. Nasty fall that will probably kill you.