Gnomeregan

Gnomeregan was the capital of the Gnome race until the invasion of troggs that led to its downfall. The city is now a mid-level instance. The few gnomes still left in the city fight desperately to keep the troggs at bay. Gnomeregan is a unique instance in that it possesses a friendly NPC section inside the dungeon itself, including vendors, a few guards, repair station, some new quests and even a mailbox.

Gnomeregan is also unique in that it has a very technological (and somewhat comical) theme.

History
From WorldofWarcraft.com:

''When the war against the Burning Legion ended, the Alliance discovered the reason for the Gnomes' sudden withdrawal. Apparently, an ancient, barbaric menace had risen from the bowels of the earth and invaded Gnomeregan. Knowing that their allies' priority was defeating the Burning Legion, the Gnomes decided to make their stand alone. Though they fought valiantly to save their beloved city, Gnomeregan was irrevocably lost.''


 * Located in Dun Morogh, the technological wonder known as Gnomeregan has been the gnomes' capital city for generations. Recently, a hostile race of mutant troggs infested several regions of Dun Morogh - including the great gnome city. In a desperate attempt to destroy the invading troggs, High Tinker Mekkatorque ordered the emergency venting of the city's radioactive waste tanks. Several gnomes sought shelter from the airborne pollutants as they waited for the troggs to die or flee. Unfortunately, though the troggs became irradiated from the toxic assault - their siege continued, unabated. Those gnomes who were not killed by noxious seepage were forced to flee, seeking refuge in the nearby dwarven city of Ironforge. There, High Tinker Mekkatorque set out to enlist brave souls to help his people reclaim their beloved city. It is rumored that Mekkatorque's once-trusted advisor, Mekgineer Thermaplugg, betrayed his people by allowing the invasion to happen. Now, his sanity shattered, Thermaplugg remains in Gnomeregan - furthering his dark schemes and acting as the city's new techno-overlord.

Summary
You can also find the Minor Recombobulator and the Discombobulator Ray schematics here.
 * Also known as: GR, Gnome, Gnomer
 * Found in: Dun Morogh, to the Far West
 * Enemy level range: 28-35
 * End Boss: Mekgineer Thermaplugg Level 34 Elite
 * Mini Bosses: Crowd Pummeler 9-60 32 elite, the Electrocutioner 6000 32 elite, Viscous Fallout, 28 elite, Grubbis 32 elite, and Chomper 30 elite.
 * Rare Spawn: Dark Iron Ambassador
 * Nice Drops:
 * Leather Feet, 68 Armor; +8 Stamina, +3 Spirit
 * 2H Mace, 29.0 DPS; +16 Strength, +5 Agility
 * 2H Axe, 32.6 DPS; +18 Strength, +7 Stamina
 * Staff, 21.6 DPS; Equip: Allows underwater breathing
 * 1H Sword, 22.1 DPS; Chance on hit: Blasts target for 10 to 20 Nature damage
 * Cloth Feet, 34 Armor; +8 Intellect, +4 Spirit, +5 Nature resistance, Increases damage and healing spells and effects by up to 5
 * Dagger, 20.5 DPS; Chance on hit: Deals 5 Nature damage every 5 sec to any enemy in an 8 yard radius around the caster for 15 sec
 * Cloth Head, 44 Armor; +12 Spirit, +15 Intellect, Use: Channels a bolt of lightning and hurls it towards all enemies in front of the caster causing 147 to 167 Nature damage. The caster is then surrounded by a barrier of electricity for 10 min
 * Ring; +5 Arcane Resistance, +5 Nature Resistance, 

Map
Here's a Gnomeregan Map with (I think) all major items and quest notes on it.

A large map from videogamemaps.net.

Gnomeregan Map from Atlas.

Quests to get before entering dungeon

 * Alliance


 * Horde
 * (This starts the quest to allow you to teleport)

Quests to get after entering dungeon

 * Neutral


 * Alliance

Tips and Strategies

 * Grime encrusted objects can be washed in the Sparkle-o-matics for random junk, and sometimes green necklaces or rings.
 * Sentry bots will happen upon your party from time to time, destroy these ASAP or risk being attacked by a lot of enemies that drop nothing.
 * There is a special type of robot in Gnomeregan that has the ability to put up a shield that reflects magic back to the caster, watch for it spell users and hold off on your spells until it disapears.
 * The Dark Iron Agents who appear near the end of Gnomeregan are very well some of the deadliest NPCs there. They will drop land mines every now and then.  When you see these land mines, DISABLE THEM IMMEDIATELY BY ATTACKING THEM!  They have only 200hp, but they inflict over 400 damage on everyone nearby. Assign someone to destroy them and make a macro to target them.
 * There is a Backdoor into Gnomeregan. The door is locked with the Workshop Key carried by the Electrocutioner 6000 or a Rogue can pick the lock. You can find it inside, just walk straight forward instead of turning to the left. On the other side of the first big room, the backdoor is ready to be opened.
 * If you are part of the Alliance you and your party can rest safely in the Clean Room; you can sell picked up and Sparkle-o-matic items to a local merchant, or even mail your items to yourself (saving bag space) or others at the mailbox.

Secrets

 * Binary punch card translations: The blocks of 1s and 0s that appear in the description page when you interact with different machines actually have meaning. They are binary representations of ASCII text.  A few examples listed here
 * Recipe: Mechanical ChickSoup
 * Gnomercy!
 * Thrall and Jaina sitting in a tree, K-I-S-S-I-N-G