Starting out with my Everquest 2 days... when you got a higher standing with different groups, you would be seen differently. Guards might hail you as you walk by where as before you were completely ignored. It's been awhile since I've played, but I believe they would even salute you as you walked by if you had the minimum "reputation".
So, what's with all of the factions in World of Warcraft? You don't really get much. At Honored, all factions will give you 10% off their goods. I'm down with that. Great idea. What bothers me slightly is that after that, you really don't get much. Think about it. "Exalted" is a pretty high word to mean "we'll sell you this one item." But at least one faction in WoW will give you something worthwhile.
The Consortium can be found throughout all of Outlands. They're ethereal smugglers, traders and thieves who are led by Nexus-Prince Haramad. The greatest thing about them is they never stop giving. Once you reach a reputation of Friendly, you get a monthly salary that you can pick up from Gezhe in Aeris Landing in Nagrand. (Edit: Thanks Lichas for reminding me.) This salary is a bag of gems. As you progress up the reputation chain, you get better and more gems in the bag. So, not only do they have items and patterns that you obtain through reputation, but you also get a monthly dividend!
I want to see more of this type of faction in the expansion. But how do you get reputation with them? The simplest way is simply to do Mana Tombs over and over again. Once you hit Honored, you'll have to get Lower City reputation so that you can can get the key for Heroic Mana Tombs.
Most likely you won't live in Mana Tombs though. You may even get sick of running instances. And I only said it's the simplest way, not the fastest. There's quests all over for these guys. If you see an ethereal, and he's got a quest, most likely it will give you Consortium rep. You can see the quests over at WoWWiki. Of particular note, you'll want to complete Seek Out Ameer which starts in Stormspire, and then A Mission of Mercy. Once you've complete A Mission of Mercy, you can then collect [Ethereum Prison Key] in Heroic Mana Tombs. These will allow you to complete other quests, and eventually summon a 4th boss in Heroic Mana Tombs.
For the solo player, besides the normal quests there's also a couple of repeatable quests that do not require a group. You can complete Obsedian Warbeads and A Heap of Ethereals (Zaxxis Insignias) by pure grinding. The other repeatable quests are Ethereum Secrets obtained at Honored and A Thousand Worlds obtained at Revered.
Myself having only reached Honored, I haven't reaped a lot of the gem benefits from these guys. I've asked people to run Heroic Mana Tombs a lot of times, and I mostly get turned down. When I do get people in there and they realize they're getting Consortium Rep, they're usually excited about that. Maybe I just need to do a better job at my marketing. LFM for Heroic Mana Tombs should now become LFM for Heroic Consortium Rep Run.