Updated Sun, Feb 24, 2008 by DarkFact
The Consortium is a faction you meet during your travels in Outland, your first contact with them will probably be within Auchindoun's Mana-Tombs, or at Nagrand when you meet the Consortium camp at Aeris's Landing. Led by Nexus-Prince Hamaad, this optional faction is full of smugglers and inter-dimensional beings called 'Ethereals', and are only concerned with making profit off of the planets they visit. You will be able to get friendly or better with them should you help them with repeatable quests, or alternatively, clearing the Mana Tombs in Heroic setting!
The Consortium's leader is right outside the Mana-Tombs, but, in order to undertake most of the quests helping you gain reputation with them you will need to quest for the NPCs in Aeris's Landing in Nagrand, or the Domes in Netherstorm. Their Quartermaster is also in the Stormspire at Netherstorm should you want to look at what you will be able to buy as you advance in reputation with them.
There's a lot of one-time quests you may do for the Consortium, however, you will need to grind either Ogres for their beads or Zaxxis Ethereals for their badges, at above honored should you want to do it by yourself.
The best way to get to friendly is to turn in 10 Oshu'gun Crystal Fragments or 3 Pairs of Ivory Tusks at Aeris's Landing as soon as you can, at 250 reputation per turn-in, you will be getting to Friendly soon, and can save your reputation gains from quests for over Friendly. Alternatively, if you don't want to grind this much early on, you can run Mana-Tombs and complete the quests the Consortium has for you right outside of them for a quick boost.
Characters trying to simultaneously earn reputation with the Mag'har or Kurenai and the Consortium may want to focus on killing Ogres in Nagrand, which award 10 Mag'har or Kurenai reputation per kill, and saving the [Obsidian Warbeads] for Consortium turn-ins. Doing this also nets many [Oshu'gun Crystal Powder], for [Halaa Research Token] turnins, allowing a player to effectively farm their Nagrand faction rep, Consortium rep, and half of their Halaa tokens all at the same time. The only caveat is the drop rate, which is roughly 33% for the warbeads, while it is 50% on the insignias.
If you are level 70, want a faster grind without concern for Mag'har/Kurenai reputation, and can handle the slightly more powerful Ethereals, then you may want to grind insignias instead.
You have a handful of options once you reach Honored to continue adding to your reputation. First of all you can grind Ogres in Nagrand for their Warbeads, this will also let you bump up your Kurenai or Mag'har reputation in the process, since each kill gives you 10 reputation with them as well.
Another option is to grind Zaxxis Ethereals, 10 of their insignias will net you 250 reputation at Area 52's Consortium NPC. Be careful in this area as they respawn very quickly! This is the ideal place to grind Ethereals though, since a combination of a Mage and a Tank (or another AoE class) will let you kill off many of them at once and collect loot very fast. The Zaxxis Ethereals do not have ranged attacks, so you're able to mass them easily.
Finally, you may obtain Ethereum Prison Keys from all Ethereals in Outland, and use them to open Ethereum Prisons in Netherstorm. These will either yield a random NPC to give you reputation with their faction for saving them, or a level 71 non-elite monster you may kill for a Prison Badge. These prison badges may be turned in for 250 reputation.
In addition, you may receive a random blue-quality item drop from these monsters.
The only dungeon you may visit to boost your Consortium reputation is Mana Tombs, and only in Heroic setting after the first time you clear the place for its quests.
Quests - ~8000 Reputation - Nagrand, Auchindoun, Netherstorm Quests
Ivory Tusk (3) - 250 Reputation. Good until Friendly
Oshu'gun Crystal Fragment (10) - 250 Reputation. Good until Friendly
Mana-Tombs (Heroic) - ~2400 reputation (full clear)
Obsidian Warbeads (10) - 250 Reputation. Good until Exalted
Zaxxis Insignia (10) - 250 Reputation. Good until Exalted.
In addition to getting access to several epic-quality items and recipes at the Stormspire's Quartermaster, once you hit Friendly, you are able to visit the NPC Gezhe in Aeris's Landing in Nagrand once per month to obtain 'payment' for your efforts. Your payment is a bag of jewels, which wil contain a random amount of green and blue jewels depending on your reputation. The higher your reputation, the better the quality and amount of the items you obtain!