Skinners and Leatherworkers can make some nice, easy gold by skinning Jormungars in Northrend. For some time now, each Jormungar Scale has been selling for 50-100g in the Auction House when sold in very small quantities to make them appear more rare.
On top of scales you will also receive Arctic Furs from time to time. These often sell for even 3x more than scales!
If there's more competition on your realm and the prices are smaller, a Leatherworker can turn these scales into Jormungar Leg Armors that often sell for even 1000-1300g due to no one else making them and Brutal Gladiators still need their pants enchanted.
Best mobs to skin:
There are also lower level worms in Dragonblight, but they have about 10% smaller drop rates for scales when skinned.
If they're selling for less than 20g on your realm, it would be wise to buy them all and make even more gold!