The Ashikar mobs in Lower Abyss drop quite a few valuable materials that can be used in Crafting powerful gear. The mobs are level 26-27 and can easily be solo'd by anyone level 24+. The only downside of being here is you're in the Abyss which means you can get ganked quite easily. The items that are worth farming for here are:
Cold Balaur Blood Stain
Thick Balaur Horn
Tough Balaur Meat
Vicious Mind of Wrath
Each of these items will net you a pretty penny in the AH. The Balaur in the Lower Abyss have a worse chance to drop these materials then the Balaur in the Upper Abyss. However you can kill these much faster and chances are you'll run into lower level players which wont pose a threat to you at all. Below is a map of where I like to farm these guys in the Lower Abyss:
NOTE: Around level 34 the Balaur will stop dropping loot for you because your level is too high.