Honor Hold
http://www.wowwiki.com/Honor_Hold
Honor Hold can be one of the most rewarding and yet one of the most frustrating reputations to grind. They have something for everyone, and yet, to prepare for their grind is to temporarily put off nearly all quests in Outland, especially if you enter at 58, since many of the alternate quests will not be available to you. Speaking of, those alternate quests are found with goblins (to be found south of Honor Hold and north of Thrallmar), the Temple of Telhamat (Northwest part of the Hellfire Penninsula zone), Telredor (Northeastern Zangarmarsh), and Orebor Harborage (Northwestern Zangarmarsh)
The first part of the reputation grind is deceptively easy, but can be very tedious. To go from Neutral to near Friendly takes killing 600 of the Shattered Hands non-elite Orcs that are found either within the central canyon or along the shattered north-south wall extending from the center of said canyon. Many of these orcs are 61 and 62, so while this part is functional when you are on your own at 58, it's much, much easier to do with a highbie. Most of us-- check the roster-- are definitely willing to do so; for 70s, for example, the grind may be trivial, knocked down to one or two hours at most. If you're lucky enough to be coming in with or near another new entrant to Outlands, it's much faster in a group.
The next part has two possibilities. I favor the front-loaded version and Nataliya favors and endgame version. The frontloaded version rests on the fact that while quests give reputation forever, the hellfire ramparts and blood furnace instances give out at 5999/6000 into Honored. This is roughly 10 Ramparts runs (~600 per run); each blood furnace run is worth 4/3rds of a ramparts run (~800 per run) Both of these instances are blessedly short, and have some truly useful blues that can and will be useful until you start replacing it with L68-70 loot. The problem here is twofold-- finding a group, and the number of repetitions. Now, if various highbies are on and unbusy, it only takes 1-2 (depending on your class) to run you through. I've found that 2 highbies can effectively demolish an instance; the remaining three slots can be taken up with virtually anything. It's certainly EASIER if at least one healer and one tank is present, of course. PUGs are also available; while often frustrating, it's worth pointing out that (not including auctioning of greens/melts/vendoring blues), a single ramparts run nets about 6-8g,w hich will usually be more than enough for repair bills.
If you complete this series, you will be able to start the Hellfire quests when they are (relative to your XP and gear) fairly easy, and get roughly 10,000 reputation from completing quests. This is not enough to hit revered, of course; but it does mean that that, if you do the key quest and the initial quests for shattered halls, a _single run through shattered halls_ will be sufficient to get you to the sweet stuff at Revered. Furthermore, there is a single quest-- which I urge you to do as often as possible, even once you've left hellfire-- that always grants 150 reputation per day, the token-earning quest to capture the various pvp objectives in Hellfire. It would only take 14 of these to reach revered with Honor Hold.
However, as Nataliya has pointed out, this is, to an extent, trading ramps runs now for ramps runs in the future. No matter what we do, we will almost certainly have to run many, many heroic ramparts and heroic blood furnace runs in the endgame. The blues there are in some cases more specialized and comparable for certain builds to Karazhan purples, and the epic drops from the endbosses are tremendous, not to mention the value of the badges of justice and primal nethers. His suggestion is to instead simply begin questing as soon as you reach 2999/3000 to friendly after destroying your 600 orcs. This will leave you at 4-6K rep, depending on how many Ramps and BF runs you do, towards Revered, a not inconsiderable amount. Many of the reputation rewards for revered are unusable until 70 in any event. This also means that you have more questing available to you earlier on.
My personal take on it has been to do the frontloaded version. A single awkward shattered halls run will leave me as a much, much better healer for the second and third and so on towards mastering Exalted and the Heroics. However, my experience has been eased; I'm partnering with a wonderful shaman who makes doing red quests possible. This may not be available to everyone. Whatever you choose to do, know that you'll have support from the rest of us.
Cenarion Expedition
http://www.wowwiki.com/Cenarion_Expedition
Cenarion Expedition is quite possibly the easiest reputation set to get to honored. Once you reach 60, go to the guild vault and take as many Unidentified Plant Parts as you find there. Don't worry; you'll be paying it back later; actually, while you're doing it, . Then buy, or talk to a highbie to grind out (It's not a huge burden to do so, as the best routes for grinding UPPs give sporeggar rep and are awesome for herbalists-- see below. Still, buying your own is best.
) to get you to 360 unidentified plant parts. Turn these in at the (unfortunately non-Flightpathed) Cenarion Expedition outpost at the Hellfire entrance to Zangarmarsh. Bam, you're honored. I highly recommend NOT doing any quests until this point. Not only do the quests give rep up to exalted, but each turn-in nets you a chance to get Uncatalogued Species, which CAN be turned in after honored for yet _more_ reputation.There's nothing else special about these guys. There are sufficient quest hubs in Zangarmarsh, Terrokar, and Blade's edge to get you to at least revered. I would recommend holding off on doing any quests that involve the Dead Mire, Funggor Cavern, or really, anything to do with Sporeloks, Bog Giants or Marsh Dredgers until you're 62, though, because...
Sporregar
http://www.wowwiki.com/Sporeggar
At 62, you'll be able to do the unfriendly -> friendly turn-ins for the Sporeggar. These are worth ~750 per quest up to friendly, and mainly consist of Mature Spore Sacs and Bog Lord Tendrils, which should also be in the bank, and if not, are again easily purchasable or grindable. Once you reach neutral, I recommend taking a break just long enough to turn in 10 flamecap mushrooms-- the quest won't be available after friendly, and while it's better to save MOST of your mushrooms for buying from the spore-guys, it's worth turning in 10 just once to get the XP and cash. The initial turn-ins are found just east of the Spawning Glens in Southwest Zangarmarsh. Their town is slightly north of there.
Past that point, you're free to do quests, turn-ins, and so on and so forth; quests last you forever, including one repeatable that's the most directly efficient way to get rep, killing bog lords and bog giants gets you rep through revered, and killing marsh dredgers and whatever the other guys are in Funggor Cavern gets you rep up to Exalted. I _highly_ recommend starting with the Bog Lords and Bog Giants, though. These suckers drop UPPs for your alts or lowbies coming up, ditto bog lord tendrils. Furthermore, they drop motes of life, and while primal lives are the second cheapest primals, they are -very-, very useful. Furthermore, if you're an herbalist, you can actually _skin_ these guys for greys, herbs, and _more_ motes of life.
Aldor or Scryer
http://www.wowwiki.com/Comparison_of_Al ... er_rewards
http://www.wowwiki.com/Aldor
http://www.wowwiki.com/Scryers
http://www.wowwiki.com/Augments#Inscriptions
http://www.wowwiki.com/Comparison_of_Al ... ng_Recipes
http://www.wowwiki.com/Comparison_of_Al ... st_Rewards
The choice between Aldor or Scryer is a tough one, that can sometimes come down to very narrow determinations based on your craft, or quest rewards, or even just the shoulder inscriptions. I heartily recommend you research on the above pages. I should note that we're currently deficient in Scryer Leatherworkers and Blacksmiths, but, please, make the choice that is best for you, not just best for the guild. Time will get us plenty of both.
At level 60, you will be able to do an introductory string of quests in Shattrath-- mostly walking around, I'm sorry to say-- that will culminate in you being able to pick allegiance with either the Aldor or the Scryer. If you are a Draenei, you will automatically be friendly with the Aldor, though completing this introductory quest will still give you significant reputation with Aldor, or you can use it to switch over to Scryers immediately.
At level 62, you will be able to turn in Marks of Kil'Jaeden (aldor) or Sunfury Signets (Scryer). Again, many of these will be available in the guild vault or the auction house. Non-Draenei, or Draenei with Scryer, will require 220 of their respective turn-in to reach Honored. I recommend this for four reasons. First, intermittently at the start but growing in intensity, you will get reputation quests that will last you until Exalted, and it's good to get it done early. Second, crafting recipes are available fairly quickly, and while they may be out of your personal use-reach, some of them can be quite lucrative to the right clients. Thirdly, one of their reputation rewards (the shoulder inscriptions, which can only be purchased through reputation-turn-in secondary tokens anyway) are available from honored on, and can be very useful in the long run. Finally, getting Scryer or Aldor rep gets you Sha'tar rep until you're honored with the Sha'tar.
Past that point, you're pretty much on your own; there are quests and rep turn ins and so forth that will last forever. These guys are based in Shattrath, though they have major quest hubs in Netherstorm and Shadowmoon valley. Aldor rep Marks drop from demons and their cultists (Shadow Labs is good here, as are various demon camps-- Auchindon and Sethekk Halls might drop them too, but I don't recall); Scryer rep marks drop from Blood Elves (found all over the place, but especially in Tempest Keep, as well as various outposts)
Sha'tar
http://www.wowwiki.com/Sha'tar
Also sort of simple. On the good side, you can get to honored really quickly with these guys, and they have some of the best rewards in the game. Unfortunately, once you DO get to Honored there is NOTHING you can do except quests... and dungeon runs, _all_ of which (at Tempest Keep) require a flying mount. That's 1100g, no faction discounts available. A long ride, but well, well, well worth doing. Based in Shattrath, though the quests will send you all over the place, and Tempest Keep is in Netherstorm.
Lower City
http://www.wowwiki.com/Lower_City
Also some fairly nifty rewards and fairly simple. Technically, you could run from neutral -> friendly on Arakkoa feathers, and then from friendly to honored on Auchenai Crypts runs. There is, however, no real reason to wait. Sethekk Halls only really requires L68, and running it at L70 is rather simple. It now gives reputation clear through Exalted. Shadow Labyrnith, the L70 run, is required for the Karazhan Key quests, and therefore is relatively easy to get a group to hit it with. To be honest, I would not recommend frontloading these guys; it's not going to be that hard to get Exalted with them. Based in Shattrath and terrokar
Kurenai
http://www.wowwiki.com/Kurenai
Again, fantastically easy to do. Get neutral with them from quests in Zangarmarsh, and then just go out and do their quests in Nagrand. Almost every humanoid mob gives 10 reputation with Kurenai, including the ogres who drop obsidian warbeads that (a) can be turned in for reputation with the Kurenai and (b) more importantly, can be turned in for reputation with Consortium. Based in Telaar in Nagrand with openers at Orebor Harborage in Zangarmarsh.
The Consortium
http://www.wowwiki.com/Consortium
An incredibly rewarding faction, the Consortium has a number of sweet recipes and gear that can be purchased. At level 64, you can begin turning in 3 pairs of ivory tusks from the wild (not bull) elekks in nagrand or 10 oshu'gun crystal fragments from the evil ethereals/ground drops near them by the huge crystal of Oshu'gun in southwestern nagrand. These are not BoP, so they may be in either the guild vault or the auction house, but are also very easy to grind. 12 turn-ins (you should do at least one of each for the xp and cash) will get you from neutral to friendly, at which point the consortium will give you a bag of gems each month. The gems within have quality commensurate with your reputation with the Consortium. The initial turn-ins as well as some quests are in Aeris Landing in Nagrand; the Mana Tombs are at Auchindon in Terrokar (and require honored with Lower City to go heroic), and a major secondary quest hub is found in the Netherstorm.
At this point, you have two options. Originally, since there is only one dungeon (mana tombs) that gives rep with these guys, it was the best plan-- which I am still considering following-- to do 6-8 or so runs through the Mana Tombs to gain Honored with them. There's good loot in there, anyway. However, the daily dungeon and daily heroic dungeon give 250 and 350 Consortium reputation each, every day. Not to mention that Heroic Mana Tombs has some incredibly nifty gear, and there's at least one quest that goes in there as well. As a result, skipping the intro runs merely sets you back ~10 days later on. In either event, it's pretty easy to push hard for Consortium Rep, which is definitely a good thing. I note that later grinds of consortium rep can be coupled with kurenai grinds by going after the ogres in Nagrand.
Keepers of Time
http://www.wowwiki.com/Keepers_of_Time
Another faction that's easy to get reputation with that has fantastic rewards, the Keepers of Time are based in Tanaris, at the Caverns of Time. The rewards of reputation for completing their quests are so high that by the end of your _first_ Black Morass/Dark Portal run at 70, you should be nearly to revered. Subsequent runs are very high on reputation and have significantly good drops. My one major recommendation here is that you do the intro quest for these guys as soon as it becomes available-- at 66, as far as I recall; it involves walking around and listening to a Keeper yack at you. Best to get it out of the way ASAP.
Ogri'la and Sha'tari Skyguard
http://www.wowwiki.com/Ogri'la
http://www.wowwiki.com/Sha'tari_Skyguard
Post-70 reputation factions that require flying mounts and a series of quest chains to do. They also involve daily quests, so, effectively, there is no need to do a /special/ grind; you'll be doing it for money eventually anyway. These guys have bases in Blade's Edge and Terrokar, but are not accessible without flight and certain prereq quests.
Netherwing Dragonflight
http://www.wowwiki.com/Netherwing
If Ogri'la and Sha'tari skyguard are post-70, the Netherwing are post-post 70. Getting to neutral with them effectively requires a flying mount; getting past neutral requires 300 riding skill. That's a cost of 5000g. The end rewards are nether drake mounts, quite possibly the coolest non-raid accessible epic fliers except for the top gladiator award (which is a special kind of nether drake anyway!). Something for the future.
Based in Shadowmoon ValleyThe Violet Eye
http://www.wowwiki.com/Violet_Eye
Endgame 10-man raiding at Karazhan. Not entirely out of our reach, but very simple-- the quests and reputation are simply done to get into the instance, and then grinding within it. Based at Karazhan itself, found in the Deadwind Pass between Duskwood and the Swamp of Sorrows.
Ashtongue Deathsworn and The Scale of the Sands
http://www.wowwiki.com/Ashtongue_Deathsworn
http://www.wowwiki.com/Scale_of_the_Sands
Endgame raiding factions in 25-man instances. Not likely in our future for some time.