I found this post on the WoW forums in the off topic section so I figured I'd post it here as well. It is a list of all useful farming locations updated for Cata. Only the videos were posted but on each video it looks like there is a link to an actual guide for each location.
(music is sometimes a bit rambunctious but you can't really complain it's such helpful information!)
Volatile Fire Farming in Twilight Highlands - YouTube - Almar's WoW Farming Guides - Volatile Fire Farming in Twilight Highlands
Volatile Water Farming in Twilight Highlands - YouTube - Almar's WoW Farming Guides - Volatile Water in Twilight Highlands
Volatile Earth Farming in Twilight Highlands - YouTube - Almar's WoW Farming Guides - Twilight Highlands Volatile Earth
Volatile Air Farming in Twilight Highlands - YouTube - Almar's WoW Farming Guides - Volatile Air in Twilight Highlands
Volatile Fire Farming (#2) in Twilight Highlands - YouTube - Almar's WoW Farming Guides - Volatile Fire at Humboldt's Conflagaration
Embersilk Cloth Farming in Uldum - YouTube - Almar's WoW Farming Guides - Embersilk Cloth in Uldum
Embersilk Cloth Farming in Twilight Highlands (1) - YouTube - Almar's WoW Farming Guides - Embersilk Cloth in Elementium Depths
Embersilk Cloth Farming in Twilight Highlands (2) - YouTube - Almar's WoW Farming Guides - Embersilk Cloth in Glopguts Hollow (Twilight Highlands)
Volatile Air Farming in Uldum - YouTube - Almar's WoW Farming Guides - Volatile Air Farming in Uldum
Blackened Dragonscale Farming in Twilight Highlands - YouTube - Almar's WoW Farming Guides - Blackened Dragonscale Farming in Twilight Highlands
Embersilk Cloth Farming in Twilight Highlands (3) - YouTube - Almar's WoW Farming Guides - Embersilk Farming in Twilight Highlands
Lost City of Tol’vir Farming - YouTube - Almar's WoW Farming Guides - Lost City of Tol'Vir Skinning
Savage Leather Farming in Twilight Highlands - YouTube - Almar's WoW Farming Guides - Savage Leather Farming in Twilight Highlands
Embersilk Cloth Farming in Deepholm - YouTube - Almar's WoW Farming Guides - Verlok Stand Embersilk Cloth Farming
Mount Hyjal Savage Leather Farming - YouTube - Almar's WoW Farming Guides - Setharia's Roost Savage Leather Farming
Embersilk Cloth Farming in Deepholm (2) - YouTube - Almar's WoW Farming Guides - Embersilk Cloth at Fractured Front in Deepholm
Mount Hyjal Vendor Trash Farming - YouTube - Almar's WoW Farming Guides - Mount Hyjal Vendor Trash Farming
Quite possibly the best farming location ever - YouTube - Almar's WoW Farming Guides: 700 - 1000g an hour Icecrown "Gold Mine" Cave