The best thing about this - It's soloable, and thus bound to get nerfed within a few days.
Should you team up with a lvl 90, you can expect to get about half the xp per kill, but the mobs will obviously die much faster and you get to kill more of them.
You can get to the island through the regular means: swimming/running with potion of water walking, getting a friend to fly you in or summon you.
What we will be killing are Spotted swarmers
Larvae with 80k hp that keeps together in packs
And windfeather chick
Birdlets at 160k who are also in packs.
There are a bunch of lesser mobs with less than 300k hp, almost everything on the island gives the same amount of xp, but these are the easiest to kill in numbers by far.
For references, the mobs give 16k xp at 87 and 19k at 88, and 22k at 89. Unrested.
What is good about these, is that they are mostly left alone, so we can still level at a decent pace during active hours.
We'll focus on the larvae, they reside around Old Pi'Jiu:
at 87 you can expect maybe up to 2m xp from one full round around Old Pi'Jiu, killing swarmers, chicks and maybe even some ironfur herdlings if you got time to spare.
The swarmer has a spawn timer on about 6 minutes, this can easily put you on 20m an hour at 87.
You'll get some timeless coins and a little more than 1 gold from each pack, I don't believe they're skinable either. Maybe an occasional timeless item or a mote of harmony, but don't expect this to be a moneymaker. Potion of luck does not work either.
The only thing to watch out for is a stacking poison debuff and people with censer, needlessly to say, you are a free bloody coin and you might be better off with the debuff anyway.
If you're doing this solo, I suggest you get some nice gear from the auction house and dungeons, enchant it and flask up. That'll make it all so much smoother. Eventually you will also get Book of the ages, Dew of eternal Morning and singing crystal to ease the process further.
Also, expect downtime after being ganked and when running around to tag rares for their goodies.
If you run with a lvl 90, there's huge amounts of small Great turtle hatchlings between the landings.
Should you stumble upon the Legends of the past you'll also find these turtles to be fun and easy to kill.
Edit: It is probably worth mentioning that I did this with a fairly spoiled brewmaster monk, so I had really decent aoe, survivability and healing, which meant fast kills and no downtime.
Edit 2: I've tested this with a sub 85 char, and I can report that it also works really well to boost characters of at least lvl 83 here. I'm eventually going to test with chars down to 80, but it's reasonable to assume it'll also work well.
Edit 3: I figured that at this point it makes sense to include a boosting guide too: My preferred faction neutral route is as following:
Yellow dots are swarmers, white dots are cranes and brown dots are turtles, all of which can be masspulled, if you can handle it. Also try to catch Gu'chi The swarmbringer on his path, the blue circle, when he spawns, as he has about 20 Swarmers with him.
The good thing with all of these packs, is that you only have to attack one, to have the whole pack running at you, so they are very easy to invite to AoE parties.
Depending on isle traffic and how fast you can kill the mobs, you might consider cutting the red line shorter with the stippled line. I find focusing on swarmers and turtles to be most effective, as they are the easiest to take down in large numbers, but again, it all comes down to what the booster can handle.
Some tips when boosting include utilizing Death Knights' control undead on pi'jiu brewmasters: worl...ling-85-a.html
If you're not a Death Knight - don't despair, The pandarens at Old Pi'jiu drops some semi-rares brews that can help the boost - if you care to spend some time farming them. These are namely Bubbling Pi'jiu Brew, Thick Pi'jiu Brew and Misty Pi'jiu Brew. These are sadly only usable at level 90, but they are still highly usable when boosting. The 2 former has an insane dps, and the latter has some dps, but mobs still die in seconds. They drop from their respective Pi'jiu pandarens, and last for 10 minutes.
Edit: Since the thread has grown quite large and the information and experiences shared in replies are buried, I'll add some of it here:
The Main Thing to remember is that if you can't Crowd Control the Swarmers, you can avoid their Poison Spit by running just far enough away from them to make them move.
Solo Leveling Mini Class Guides For Swarmer:
Monk - Brewmaster:
Glyph Of Breath Of Fire
Dizzying Haze, Keg Smash, Breath of Fire, Spinning Crane Kick, Leg Sweep, Expel Harm, Chi Burst and Detox
Open by throwing a keg so they move towards you, let them gather, run in and keg smash followed by Breath of fire. Use spinning crane kick twice and use another Breath of Fire. Use Keg smash as soon as ready, followed by another breath of Fire. Should something happen and they get to attack you before you have another Breath of fire ready, use Leg sweep. Mix in Expel harm, chi burst and detox as you see fit.
Warrior - Arms:
Shockwave for control or Bladestorm for fast kills
Mass Spell Reflection for spits
Heroic Leap, Charge, Thunderclap, Mass spell reflection and Shockwave or Bladestorm
Credits to Dcrvtec
Druid - Feral
Pull With Faerie Fire, let them gather, dance in and out of range, use Trash and Swipe.
Paladin - Retribution or Prot Depending on gear
Very well geared - Retri
Mediocre geared - Prot
Consecration, Avenger's Shield, Hammer of the Righteous, Flash of Light, Cleanse
Put down Consecration and Dance back and forth while the swarmers are standing in the glow. Place a new consecration when they are almost out of the last one. It takes a little longer to kill them, but if you do it very controlled, they shouldn't even be able hit you at all. Cleanse and heal as seen fit.
Warlock - Destruction
Grimoir of Sacrifice, Shadowfury
Rain Of Fire, Fire and Brimstone, Incinerate, conflagerate and immolate.
Use RoF to build embers then activate FnB. Then spam incinerate and throw some conflagrate and immolate into the mix.
Thanks to Gooey
Priest - Shadow or Disc
Shield, Renew and Mind Sear. Move if they get too close
Mage - Frost
Glyph of Ice Lance
Frost Nova, Blink and Blizzard, Frozen Orb and Ice lance
Pet Frost Nova, Frozen Orb Ice Lance
Credits to Gooey
Rogue - Assassination:
Deadly Poison and Mind Numbing Poison
Fan of knives and crimson tempest
Dance in and out of range.
Credits to Arnoud
Shaman - Elemental
Glyph of Chain Lightning
Just spam chain lightning while moving
Credits to Gooey
Death Knight - Frost
Hunter - Survival:
Frost Trap and Multi Shot