Leatherworking

Horde

Apprentice (to 75)
Chaw Stronghide (Bloodhoof Village, Mulgore)
Dan Golthas (The Rogues Quarter, Undercity)
Kamari (The Drag, Orgrimmar)
Mak (Thunder Bluff, centre of Thunderbluff, near Cairn Bloodhoof)
Shelene Rhobart (Trisfal Glades, along the road from Undercity to The Bulwark)
Waldor (Wailing Caverns, in the left-hand eye socket. You'll have to go round the back of the hill, go up and over and drop in)

Journeyman (to 150)
Arthur Moore (The Rogues Quarter, Undercity)
Brawn (Grom'Gol Base Camp, Stranglethorn Vale)
Karolek (The Drag, Orgrimmar)
Krulmoo Fullmoon (Camp Taurajo, The Barrens)
Tarn (Thunder Bluff, centre of Thunderbluff, near Cairn Bloodhoof)

Expert (to 225)
Una (Thunder Bluff, centre of Thunderbluff, near Cairn Bloodhoof)

Artisan (to 300)
Hahrana Ironhide (Camp Mojache, Feralas)
Dragonscale Leatherworking Quest - Starts with Thorkaf Dragoneye (Badlands, just to the South of the back entrance to Uldaman)
Elemental Leatherworking Quest - Starts with Brumn Winterhoof (Arathi Highlands, as you come into Arathi from Hillsbrad, he's on a little hill just past the
first left hand turn)
Tribal Leatherworking Quest - Starts with Se'Jib (Stranglethorn Vale, little hut to the South of the Mizjah Ruins, across the river)*
*You must complete the Wild Leather quests from Jangdor Swiftstrider (Camp Mojache, Feralas) before you can train for Tribal Leatherworking

Master (to 375)
Barim Splithoof (Thrallmar, Hellfire Peninsula)
Darmari (Shattrath City)

Alliance

Apprentice (to 75)
Adele Fielder (Goldshire, Elwynn Forest)
Darianna (Craftsman's Terrace, Darnassus)
Gretta Finespindle (The Great Forge, Ironforge)
Nadyia Maneweaver (Teldrassil, just off the road that runs between Darnassus and Dolanaar, near the road that leads up to The Oracle Glade)
Randal Worth (Old Town, Stormwind City)
Waldor (Wailing Caverns, in the left-hand eye socket. You'll have to go round the back of the hill, go up and over and drop in)

Journeyman (to 150)
Aayndia Floralwind (Astranaar, Ashenvale)
Faldron (Craftsman's Terrace, Darnassus)
Fimble Finespindle (The Great Forge, Ironforge)
Simon Tanner (Old Town, Stormwind City)

Expert (to 225)
Telonis (Craftsman's Terrace, Darnassus)

Artisan (to 300)
Drakk Stonehand (Aerie Peak, The Hinterlands)
Dragonscale Leatherworking Quest - Starts with Peter Galen (Azshara, in between The Forlorn Ridge and The Ruins of Eldarath)
Elemental Leatherworking Quest - Starts with Sarah Tanner (Searing Gorge, South East corner)
Tribal Leatherworking Quest - Starts with Caryssia (The Lower Wilds, Feralas)*
*You must complete the Wild Leather quests from Pratt McGrubben (Feathermoon Stronghold, Feralas) before you can train for Tribal Leatherworking

Master (to 375)
Brumman (Honor Hold, Hellfire Peninsula)
Darmari (Shattrath City)