Many people have caught on to this, but I enjoyed it a lot post-Beta since I had to wait a bit before getting the expansion :P
There is a place in Valley of the Four Winds most Pandaria players remember, the town of Halfhill.
Halfhill Defender - NPC - World of Warcraft
This town has a neutral flight master that does not agro, an unguarded inn, and also a safe zone on the SouthWestern side of town (name of Cell is Sunsong Ranch).
The idea is that people can get easy HKs/ganks/bloody coins on pvp servers as the opposing faction logs into the inn and lands on the flight path.
Also many level 90-100 players cluster at the market proper next to Sunsong Ranch.
Mecha-Blast Rocket
The idea here is to pick a target with 65k health or less and have the item Mecha-Blast Rocket in your inventory.Mecha-Blast Rocket
Item Level 100
Use: Deals X Fire Damage + X Damage per second (level dependent) to an enemy up to 0 to 40 yards away. (1 Min Cooldown)
Requires Level 91
Max Stack: 20
This is a simple engineering product usable by any class that is level 91 (don't need to be engi),
and incidentally these rockets proc weapon enchants such as Shattered Hand and can benefit from abilities such as warrior bleed effects and trinket dots etc.
I.e. a player can enrage or blow some other such cooldown, blow abilities that increase crit rating or spellpower, etc. any damage buff should work for now.
Those comfortable with wasting a button can macro this to a favorite spell.
Players at the market can be safely rocketed by players who can trinket or ability out of guard's net,
as long as the player takes care to drop from the air into the zone Sunsong Ranch or attempt to reach the enemy player via a roof.
Many classes (humans lol) can figure out a way to access the Ranch to drop guard agro.
you should still see HK or Bloody Coin when the player dies in spite of the zoning out.
also players in the inn can be rocketed without guard problems, just like Binan Village, and the flight master can't agro so hehe. good for ganks
Don't forget to check all pet battle places, fish bot banks, the Silken Fields and Skyrange.
Method 2 is farming the portal of Grim Batol or Stonecore for the swarms of pvp 90 druid bots.
Super easy way to get 1000 hk achieves and also bloody coins galore.
eventually though the bot owner might come and grief you. so look out.
a class that can aoe stunlock, freeze, or fear is best.
although the rocket does half damage at lvl 91 it's extremely useful and every player should carry like 60 of these at all times, lol.
The cooldown is a paltry 60 seconds out of combat and it does NOT share cooldown with the Goblin Glider, so any flying toon at low health is in imminent danger.
It's quite simple to farm up gold from selling the Vengeful Porcupette battle pet from Timeless Isle at 100 bloody coins a pop.
Also those who never got the Ashhide Mushan in Pandaria should be able to get it pretty fast using these methods.
The more you gank the more enemies come, so /3 is your friend