Borean Leather

This is a favorite spot of mine that requires a high lvl character.

Location: The Oculus (located in the Borean Tundra right on top of the Nexus entrance and below the raid entrance for the Eye of Eternity)

Where to farm: The oculus is made up of what I call tiers/levels and where you want to farm is on the very first tier there are lots of dragonkin, both whelps and the full grown.

My recommended tactic: A requirement for this to be the best spot you've ever encountered is that you are at least lvl 85 and well equipped if you're like me and lvl 90 it's a cake walk.

Enter the instance and if you're not mounted, mount up and run through all the mobs of dragonkin pulling the whole tiers worth of mobs. Run to the end where there are three of the large dragonkin standing near a blackish light anomaly which ports you to the next platform. Pull those three and back track a little bit. Put out your AoEs and they drop like flies. With the newish AoE looting this is the best place by far to farm Borean Leather. Skin all the corpses and head back to the dungeon entrance, port out, reset, and go back in.

In one run which takes no more than five minutes as a 90 I get between 34-43 leather per run. And please, for those of you that read this and see how awesome it is, please don't post this all over the internet as it will most likely be nerfed to oblivion if Blizzards hears too much of it =D Cheers!

***UPDATE***
12/13/2014 For some reason the Heroic Difficulty has been nerfed really badly. I only got 8 leather on heroic but normal, which you can reset unlike heroic, still gave me 31 leather from one pull.

As a kind of compendium of the suggestions for leather farming:

Source 1: Dragon mobs in Violet Hold.
Pros: If you are the only skinner, you can get some easy stacks from just skinning the elites.
Cons: Finding a group for heroics.

Source 2: Cavedweller Worgs
Pros: Low-HP, spawns in pairs, Jormungar worms also spawn in the area. Also getting Worm Meat and Worg Haunch.
Cons: You end up very deep in a cave, sometimes the Jormugar worms damage the wolves to the point where you can't loot them.

Source 3: Gorillas in Sholazar Basin.
Pros: 3-4 good groups of mostly neutral apes, easy and safe to AoE down.
Cons: Highly annoying vendor trash, can sometimes get a lot of competition.

Source 4: Gundrak Raptors
Pros: Each time you skin them, you get 1-3 pieces of leather instead of just one. Also chance of getting rare pet.
Cons: Relatively spread out, cannot really group them up.

Source 5: Enraged Mammoths
Pros: By the time you make one circuit, they will have respawned at the start. Also getting Chunk o' Mammoth (sometimes dropping 2 at a time).
Cons: Technically a questing mob, sometimes humanoid pats will get in your way.

Personally, I pick the source depending on what else drops that I want at the time. If I want to refresh my stock of Worg Tartare, then I will hit up the caves. If I want to make some coin selling Chunk o Mammoth, I will farm the Mammoths. And so on.

An alternative to the Cavedweller Worgs, I found the gorillas in the Sholazar Basin to be wonderful. As a feral druid, i run into the packs and use demo shout, becuase they are not hostile mobs, so i can get the aggro. They I just spam Maul/Swipe and take them down. The Cords of the places I farm are:

66,78 64,75 61,71 56,75

You probably won't need to travel to all of these the respawn time is really quick.