Special mention is the Darkmoon Faire Top Hat and WHEE! buff. While not always available due to the DMF being inaccessible most of the month, if you happen to be leveling when the DMF is running, it might be worth your time to go and get these. AFAIK they do stack with heirlooms, although I have not personally tested it. Fair warning: These buffs do NOT stack with each other, and the hats disappear after the DMF goes away later in the month(unless you only log in when the faire is running).
-PvP- Completely broken for some classes and I mean broken going from both sides of the spectrum, from classes destroying everyone, to classes that can't even kill another player. It's fairly common for a weak class to lose to a powerful class even if the weak class outgears them by 50+ ilvls. That's how broken PvP is and Blizzard doesn't seem to know what to do to fix it other than do blanket damage nerfs/buffs as those are the only changes we've seen.
REALMS Aerie Peak Aman'Thul Area 52 Arthas Baelgun Barthilas Blackrock Bleeding Hollow Burning Legion Cenarius Dalaran Darkspear Earthen Ring Emerald Dream Frostmourne Garona Garrosh Hyjal Illidan Kel'Thuzad Kil'jaeden Korgath Lightbringer Mal'Ganis Moon Guard Proudmoore Ravenholdt Sargeras Saurfang Shattered Hand Stormrage Stormreaver Thrall Tichondrius Turalyon Wyrmrest Accord Zul'jin Aegwynn, Bonechewer, Daggerspine, Gurubashi, and Hakkar Agamaggan, Archimonde, Jaedenar, and The Underbog Aggramar and Fizzcrank Akama, Dragonmaw, and Mug'thol Alleria and Khadgar Alexstrasza and Terokkar Altar of Storms, Anetheron, Magtheridon, and Ysondre Alterac Mountains, Balnazzar, Gorgonnash, The Forgotten Coast, and Warsong Andorhal, Scilla, Ursin, and Zuluhed Antonidas and Uldum Anub’arak, Chromaggus, Crushridge, Garithos, Nathrezim, and Smolderthorn Anvilmar and Undermine Arathor and Drenden Argent Dawn and The Scryers Arygos and Llane Auchindoun, Cho'gall, and Laughing Skull Azgalor, Azshara, Destromath, and Thunderlord Azjol-Nerub and Khaz Modan Azuremyst and Staghelm Baelgun and Doomhammer Black Dragonflight, Gul'dan, and Skullcrusher Blackhand and Galakrond Blackwater Raiders and Shadow Council Blackwing Lair, Dethecus, Detheroc, Haomarush, Lethon, and Shadowmoon Bladefist and Kul Tiras Blade's Edge and Thunderhorn Blood Furnace, Mannoroth, and Nazjatar Bloodhoof and Duskwood Bloodscalp, Boulderfist, Dunemaul, Maiev, and Stonemaul Borean Tundra and Shadowsong Bronzebeard and Shandris Burning Blade, Lightning's Blade, and Onyxia Caelestrasz and Nagrand Cairne and Perenolde Cenarion Circle and Sisters of Elune Coilfang, Dark Iron, Dalvengyr, and Demon Soul Dawnbringer and Madoran Darrowmere and Windrunner Dath'Remar and Khaz'goroth Deathwing, Executus, Kalecgos, and Shattered Halls Dentarg and Whisperwind Detheroc and Shadowmoon Draenor and Echo Isles Dragonblight and Fenris Draka and Suramar Drak’Tharon, Firetree, Malorne, Rivendare, Spirestone, and Stormscale Drak'thul and Skywall Dreadmaul and Thaurissan Durotan and Ysera Eitrigg and Shu'halo Eldre’Thalas and Korialstrasz Elune and Gilneas Eonar and Velen Eredar, Gorefiend, Spinebreaker, and Wildhammer Exodar and Medivh Farstriders, Silver Hand, and Thorium Brotherhood Feathermoon and Scarlet Crusade Frostmane, Ner'zhul, and Tortheldrin Frostwolf and Vashj Ghostlands and Kael'thas Gnomeregan and Moonrunner Greymane and Tanaris Grizzly Hills and Lothar Gundrak and Jubei'Thos Hellscream and Zangarmarsh Hydraxis and Terenas Icecrown and Malygos Kargath and Norgannon Kilrogg and Winterhoof Kirin Tor, Sentinels, and Steamwheedle Cartel Lightninghoof, Maelstrom, and The Venture Co Malfurion and Trollbane Misha and Rexxar Mok'Nathal and Silvermoon Muradin and Nordrassil Nazgrel, Nesingwary, and Vek'nilash Quel'dorei and Sen'jin Ravencrest and Uldaman Ravenholdt and Twisting Nether Runetotem and Uther
Allied races: Our new allies will join the factions and players will be able to unlock the ability to play their race. There are 6 planned for launch. Horde: Nightborne, Highmountain tauren, Zandalari troll. Alliance: Void elf, Lightforged draenei, Dark Iron dwarf. Additional races are planned for the future. Receive a Heritage Armor set, if you level an allied race character to level 110.
For reference, my previous best time abusing Method-0 in 7.3.5 was 32.4 hours(as show in the old thread). A difference of just over 8 hours; which isn't all that bad, all things considered. And I believe I made several errors along the way, which could be cleaned up in future runs. I believe that that gap could be significantly closed by using a monk's bonus, but I hate playing monk...so...yeah. YMMV