Orgrimmar is the seat of power for the Horde and the capital city of theorcs, but also has many trolls and other members of the Horde. Found at the northern edge of Durotar, the imposing city is home to the troll Warchief, Vol'jin. As with all capital cities, it has a bank, class, profession trainers, and an auction house.
Areas of Interest:
The Valley of Spirits: now flooded after the Shattering, center for Darkspear trolls--many profession and class trainers with distinctive huts and decorations.
The Cleft of Shadow: rogue and warlock trainers, entrance to Ragefire Chasm.
Goblin Slums: Subset of the Valley of Spirits, very dirty and polluted, class and profession trainers.
The Valley of Wisdom: Former location of Grommash Hold under Thrall's command, now additional pools, tauren huts, blacksmith, auctioneer, bank, guild vault, some class trainers.
The Valley of Strength: largest hub, Garrosh's seat of power in Grommash Hold, auction house, bank, Inn, guild vendors.
The Drag: links the Valley of Strength and the Valley of Wisdom, alchemy, herbalism, skinning, leatherworking, cooking, first aid profession trainers.
The Valley of Honor: battlemasters, warrior and hunter trainers, PvP vendors, blacksmithing, mining, and fishing trainers, new entrance to Azshara.
Orgrimmar to Kalimdor Transportation Methods
Zeppelins: These towers are now located on top of a rise in central Orgrimmar, instead of outside the city.
From Thunder Bluff: Krendle Bigpockets in the Spirit Rise.
From Warsong Hold, Borean Tundra: Nargo Screwbore inside the Hold, across from the lift.
From Tirisfal Glades: Zapetta, south of Brill.
From Grom'gol Base Camp, Northern Stranglethorn: Nez'raz, on top of the tower to the south.
Shroud of Cooperation: Teleports the caster to Orgrimmar, 8 hour Cooldown. This item can be purchased from a Guild Vendor upon earning the guild achievement A Class Act and reaching Honored reputation with your guild.
Wrap of Unity: Teleports the caster to Orgrimmar, 4 hour Cooldown. This item can be purchased from a Guild Vendor upon earning the guild achievement Guild Level 15 and reaching Honored reputation with your guild.
Cloak of Coordination: Teleports the caster to Orgrimmar, 2 hour Cooldown. This item can be purchased from a Guild Vendor upon earning the guild achievement Master Crafter and reaching Honored reputation with your guild.
Shattrath City, center by A'dal.
Mount Hyjal, Nordrassil.
Deepholm, right alcove of the Temple of Earth.
Sunreaver's Sanctuary, Dalaran
Tol Barad, by daily quest hub.
Tol Barad--downstairs in Baradin Hold, after winning.
Vale of Eternal Blossoms, second floor of Shrine of Two Moons
Portal from Warspear, Draenor
The Jade Forest, Honeydew Village
Stair of Destiny (by the Dark Portal), Hellfire Peninsula
Twilight Highlands, Dragonmaw Port.
Peak of Serenity, Monk only
Mages: Portal: Orgrimmar/ Teleport: Orgrimmar
The Brassiest Knuckle: requires Rank 4 Brawler's Guild
Another easy way is to take the Blasted Lands portals from other major cities, go through the Dark Portal, and then take the port by the Stairs of Destiny, Hellfire Peninsula, to Orgrimmar.