For miners, I've compiled a list of where mining deposits are to be found, what else they drop, and what level you'll need to have in order to mine the ore up and smelt it.
I've broken down each of the Outland herbs for herbalists, including the buffs they might award, which provinces have which herbs, and where the herbs tend to grow. Many herbs also drop motes and other herbs, as well.
Skinners will be interested in the list of the types of leather, hides, and scales, where best to farm them, and how profitable such a venture might be.
Along with a brief discussion of the benefits of gathering daily quests, you should leave with all the information you need to plot a quick and profitable route to skill 375.
Mineral vein locations
Fel Iron: These veins can be found all over Hellfire Peninsula, so gaining mining points should be a breeze while leveling. When you move on to Zangarmarsh, you'll find a fair amount too, especially around the perimeter. You will also find nodes in Terokkar, Nagrand, Blade's Edge, Shadowmoon Valley, and Netherstorm. Basically, any province is going to house fel iron deposits. You can also find fel iron in the Steamvault. You only need 300 mining skill to begin hacking away at fel iron deposits.
These nodes may also include gems, eternium ore, and motes of fire and earth.
Adamantite: You'll find every zone except Hellfire to be decently stocked with adamantite, including several dungeons. You need 325 skill in order to mine this, but it has a chance to drop gems, eternium ore, and motes of earth.
Rich Adamantite Deposit: These will crop up in Terokkar, Nagrand, Blade's Edge, Netherstorm, Shadowmoon Valley, and many dungeons. Like its poorer counterpart, these deposits may hold eternium ore, gems, and motes of earth. You will need mining 350 in order to start into these veins.
Khorium Vein: You might find one of these in any of the Outland provinces, so keep an eye out! These veins often drop more motes of earth and fire, eternium ore, gems, and even blue-quality gems. Unfortunately, you'll need mining 375 in order to begin gathering them.
You will find old-world herbs such as Golden Sansam, Mountain Silversage, and Blindweed in Outland, primarily in the lower 60s provinces like Zangarmarsh and Hellfire Peninsula, but I'm going to focus on Outland-only herbs.
Felweed: This herb is a staple for many potions, both cheap and expensive, and can be found in every Outland province. Because this herb is found out in the open, you'll find spawns that are easy and safe to gather, and others that seem deliberately placed between several unfriendly-looking mobs. You only need 300 herbalism to begin gathering this.
Gathering felweed may also produce motes of life, fel lotus, or fel blossom.
Terocone: Terocones are mainly found scattered around Terokkar, but you'll also find the odd one in the Arakkoan areas of Shadowmoon Valley. Harvesting fungal giants, primarily in Zangarmarsh, may also yield the odd terocone. When gathering, you may end up with motes of life as a bonus. You will need 325 herbalism in order to pick this herb.
Ragveil: Ragveil is found throughout Zangarmarsh, as well as the Coilfang dungeons. Like terocone, you will need 325 herbalism in order to begin gathering this, so if you're leveling, try to load up on felweed and dreaming glory as soon as possible. As with the herbs mentioned above, you may find a mote of life (or a few!) when picking ragveil.
Flame Cap: This colorful little herb is found only in Zangarmarsh, and doesn't spawn widely. It seems to be the rare form of an otherwise ragveil spawn. Oddly enough, it is not used in alchemy for any elixirs, potions or flasks, but is consumed as-is. Doing so will grant you a chance to strike your melee or ranged target for 40 fire damage, and may increase your fire spell damage by up to 80. The effect lasts for one minute. You may find the odd spawn in Underbog and the Slave Pens as well.
Flame caps trigger the following cooldowns; healthstones, mana gems and other consumable herbs. They do stack with potions and other such consumables. Harvesting this herb may yield a fel lotus.
Ancient Lichen: This herb is fairly plentiful, but only spawns in dungeons. As long as you're not running with other herbalists, you can pick up a fair amount during each run. You will need 340 herbalism in order to start gathering it, even in Underbog and Slave Pens, which are low-60s dungeons. You'll also find this herb in all of the Auchindoun dungeons, as well as the Steamvault. You might also end up picking it from fungal giants and similar mobs that you can 'herb.' Picking this herb may yield motes of life, or as of 2.4, a fel lotus.
Netherbloom: Netherbloom is another herb that, like dreaming glory, gives a buff when you loot it. Unlike dreaming glory, which always buffs you, netherbloom's effects, called "Netherbloom Pollen," are a chance on loot. As of patch 2.1, you will acquire a +50 buff to any of a number of stats, and no longer have a chance for a -50 debuff. Rather than motes of life, you'll often find motes of mana when gathering netherbloom. You will need a skill of 350 in order to pick up this herb, and you'll find it in Netherstorm and Botanica.
Nightmare Vine: Requiring 365 herbalism to gather, this particular herb is, in my humble opinion, the most annoying to try to acquire. It seems to always spawn in camps or other areas with densely packed level 70 mobs, although sometimes you might only end up fighting one or two.
You'll find this herb while doing your daily quests around the Throne of Kil'Jaeden, a spawn or two per forge camp while doing your Ogri'la and Skyguard dailies in Blade's Edge, and throughout Shadowmoon Valley. In fact, you can find them in the deadzone around Brutallus too.
While gathering this herb, you may end up with a nightmare seed or a fel lotus.
Mana Thistle: Mana thistle can be found while doing your daily quests on the Isle of Quel'Danas, and in the parts of Blade's Edge that require flight. It requires 375 herbalism to gather. It may produce motes of life, although mana thistle spawns produce smaller quantities than most herb spawns, yielding one, maybe two thistles.
When you pick mana thistle, you will gain mana, anywhere from 500 to 3500.
Zangarmarsh: Any herb harvested in Zangarmarsh, including the bog lords and other mobs you can harvest, has a pretty decent chance of also producing [Unidentified Plant Parts].
Knothide Leather Scraps: These can skin off most beasts in Outland, although they're more common on lower level mobs. With a 300 level skill, you can begin skinning some of the boar in Hellfire, and convert five pieces into one knothide leather.
Knothide Leather: When not made from converted scraps, this leather also drops from most any beast in Outland. You'll get a fair amount from the Nesingwary quests in Nagrand, as well as from the corpses of others on the same quests. Eventually, when you have the skinning daily quest, you might want to simply farm clefthoof for twenty minutes while you collect your residue. They'll drop scraps, knothide leather, and clefthoof leather.
Another good tip is to go into The Caverns of Time: Black Morass (or Dark Portal) and clear every beast around, exit, and reset. You'll also find a fair amount of [Netherweb Spider Silk] which sells extremely well on the AH. You will have to have completed the quests in Durnholde/Old Hillsbrad first.
If you're the only skinner in a group of five, I also find that an Underbog run can really amount to a lot of leather.
Fel Hide: For the most part, this skins from demons in Outland, although there are some warp chasers that this can be skinned from. It is most commonly used in the Felstalker set, which is often made while leveling leatherworking.
Crystal Infused Leather: My favorite source for these is basilisks, partly because the meat they drop can be used to make [Blackened Basilisk] and either used, or sold. This type of leather, in my experience, tends to not be in high demand, so I don't put stacks on the auction house anymore. Still, it is used in the Felstalker set, Netherfury set, and Flamescale set.
Thick Clefthoof Leather: This type of leather is in high demand, and sells very well on the auction house. It drops primarily from clefthoof bulls and aged clefthoofs in Nagrand. It is used in the Heavy Clefthoof set that is both widely worn, and commonly used to level up leatherworking. It can also be found in popular and expensive leg armor kits, drums, and the Enchanted Clefthoof set from the Scryers.
Wind Scales: These are used in many epic leatherworking pieces, and are thus a bit of a commodity. The scalewing serpents and felsworn scalewings in Blade's Edge, the eclipsion dragonhawks at Eclipse Point in Shadowmoon, and the swiftwing shredders in Netherstorm will all drop [Wind Scales] when skinned.
Fel Scales: These drop primarily from basilisks and ravagers around Outland, and are used in many leatherworking recipes, from common greens used to level up the skill, to the Shackled Souls epics.
Nether Dragonscales: Used in a lot of leatherworking epics, these can be skinned from drakes in Dragonmaw Fortress in Shadowmoon Valley, although it would be much easier to farm them from nether dragons on the eastern shelf of Blade's Edge Mountains, or in Netherstorm along the Celestial Ridge.
A note about the gathering dailies:
There are two types of gathering dailies that you can do, and I highly recommend doing both as soon as possible, although the dailies from the Netherwing are less profitable than those from the Shattered Sun.
Your Shattered dailies give you an excuse to go out hunting for mining nodes, kill some cobras or drakes or clefthoof, or fly around and herb. I often come away with several motes, if not a whole primal, and a few partial stacks of various herbs. On my skinner, I end up with a fair amount of meat, as well as leather.
The Netherwing gathering dailies can be a bit of a pain, although again, if you're a skinner, you'll make an awful lot of leather by the time you're done for the day.