Mobs to Kill
Level 70
Apexis Flayers (72)
In Blade's Edge Mountains, in the plateau to the north are Apexis Flayers. There are level 71s and 72s. The 72s have one of the highest silver drop rates I've found, and they're easily soloable (you have to be 70 to fly up there anyway). They drop some so-so grays that stack up fast, and Apexis Shards, and they hang out where Apexis Shards spawn on the ground. The reason this is important is that with enough shards collected, it makes it worth it to spend a Flask on these. You can get a flask with 10 shards from the devices up in Ogri'la.
Netherstorm demons (68-70)
Directly to the NW of Stormspire, just outside the dome, there are some portals surrounded by demons. Ironspine Forgelords are my favorite, along with the Cyber Forgelords. Beware the ones with the Fel Cannons...those are a pain. Anyway, they have a high drop rate of Marks of Sargeras and Fel Armaments. Currently, on my server, Marks are selling for about 75s each, and FAs are selling for about 14g. I have been getting about 4 FAs per hour, and about 20 MoSs per hour. Not bad when you throw in the occasional green items, Netherweave...oh, and the silver they drop. :) Oh...and the herbs and ore that spawn there.
Netherstorm "Island" - Socrethar's Seat (70)
Another spot I like is the "island" to the NW of Stormspire in Netherstorm. It's only accessible if you have a flying mount. There are level 70 demons there, and a big elite. The elite just stands in the middle...easily avoided. Mana Thistle and Dreaming Glory spawn all over the place there, as does Adamantite and sometimes Khorium. But the significance is the green drops from the mobs. They drop Marks of Sargeras, and occasionally a Fel Armament (not as good as the forgelords), but they drop other random greens at a pretty decent rate (around 10%), and those greens either sell really well, or have a high vendor sale rate, or have a high DE value. If you are an enchanter, I'd recommend checking that spot out. And unlike other sections that can only be reached by flying mount, this one isn't as dangerous.
Elemental Plateau
I hate to give this one away, since this is where I live these days. If you're on Eonar, say Hi to Ghalt if you see me here. The Elemental Plateau is an area that can only be reached via flying mount. It is above (and to the north) of the Throne of Elements in Nagrand. There are Water, Air, Earth and Fire elementals here. They respawn relatively quickly, and have a very high drop rate of motes. It's pretty heavily farmed. Depending on what time of day you're there, number of 70s on your server, etc...this place can be crowded. But it's still one of the fastest places to collect motes, and primals (especially fire and water) are selling like gangbusters. The mobs are close together, but can be singly pulled. It's a farmer's paradise. There's even a graveyard so if you die, you can get back to your corpse quickly. The other special tip about this place is that in the water there are 6 spawn points for Pure Water. If your fishing is high enough (I am at 330 and still use an Aquadynamic Fish Attractor), you can get motes of water very quickly from these pools. So have fun! Unless you see Ghalt there...then go away. :)
Mana Elementals in Netherstorm
If you travel to southeast Netherstorm, there's a little (destroyed) town called Wizard's Row. The two types of mobs there have a high drop rate of motes of mana, which combine to make Primal Mana. It's boring farming there, but their drop rate is good. As usual, pick the farming spot where you can kill the fastest. If Primal Manas sell for the same as Primal Waters, and you're collecting Primal Waters for your Frozen Shadowweave set (for example), but you can kill the mana elementals faster than the water elementals...farm the heck out of the mana, and sell them, then use the money to buy the Primal Waters, instead of trying to 'save' and just farm the water elems. Note: the respawns are very fast here. In fact, the more people that are farming it, the faster the spawns reappear!!
Water Elementals in Terokkar
If the Elemental Plateau is too crowded for you, and you don't have a problem killing Water Elementals that are Frost Immune, another really good spot to farm them is in Skettis in Terokkar. You need a flying mount, and there is a spot in the southeast corner of the map that is a plateau way up high, with a lake. Personally I find the mobs (birdmen) pretty tough, but the water elementals around the lake...especially near the top of the waterfall...drop motes of water at about the same rate as the ones on the Elem Plateau, and the place is usually much less crowded.